diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/destination/Destination.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/destination/Destination.java
index 7210e7547d1430fee67977c97c3f985a68031001..2d405d47137c585b7a29a02e1a503f1abd1a4170 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/destination/Destination.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/destination/Destination.java
@@ -1,14 +1,12 @@
 package de.fitko.fitconnect.api.domain.model.destination;
 
 
-import com.fasterxml.jackson.annotation.*;
-import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.annotation.JsonProperty;
 import de.fitko.fitconnect.api.domain.model.submission.Callback;
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
 import java.util.LinkedHashSet;
-import java.util.Objects;
 import java.util.Set;
 import java.util.UUID;
 
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/event/EventLog.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/event/EventLog.java
index fd14f18a42b2a290b0d1739b1b6b8682a88b87fa..4baff786651862269bfb2b27887368c4d171f9e0 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/event/EventLog.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/event/EventLog.java
@@ -21,7 +21,7 @@ public class EventLog {
   private Integer totalCount;
 
   @JsonProperty("eventLog")
-  private List<String> eventLog = new ArrayList<>();
+  private List<String> eventLogs = new ArrayList<>();
 
 }
 
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/AdditionalReferenceInfo.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/AdditionalReferenceInfo.java
index 3b208af5dbcbede00449be9e0fdc2ccd9b21977b..d28cb6ba4e2acbeeb270dcc90787656dcf338d5d 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/AdditionalReferenceInfo.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/AdditionalReferenceInfo.java
@@ -3,10 +3,7 @@ package de.fitko.fitconnect.api.domain.model.metadata;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import lombok.Data;
-import lombok.Getter;
-import lombok.Setter;
 
 import java.util.Map;
 
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/ContentStructure.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/ContentStructure.java
index 0085fa3f374cee3ff778c9b768b81276be7b5464..9931774f8418db383429f8897fa12a63aa78067a 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/ContentStructure.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/ContentStructure.java
@@ -3,12 +3,9 @@ package de.fitko.fitconnect.api.domain.model.metadata;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import de.fitko.fitconnect.api.domain.model.metadata.attachment.Attachment;
 import de.fitko.fitconnect.api.domain.model.metadata.data.Data;
-import lombok.Getter;
 import lombok.NoArgsConstructor;
-import lombok.Setter;
 
 import java.util.List;
 import java.util.Map;
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/Metadata.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/Metadata.java
index eb12ef03130fe8f5867ff0f15df14c9fabb75f04..4923277dec569b8bc5addcba4346ebda29b39e1c 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/Metadata.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/Metadata.java
@@ -3,8 +3,8 @@ package de.fitko.fitconnect.api.domain.model.metadata;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonPropertyOrder;
-import lombok.*;
+import lombok.Data;
+import lombok.NoArgsConstructor;
 
 import java.util.List;
 import java.util.Map;
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/PublicServiceType.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/PublicServiceType.java
index 154fe0918383dedcfe317db742ad131ca6448cab..407f84dcf124e8f4f897eb4b28b154a3d17b2ccb 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/PublicServiceType.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/PublicServiceType.java
@@ -3,10 +3,7 @@ package de.fitko.fitconnect.api.domain.model.metadata;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import lombok.Data;
-import lombok.Getter;
-import lombok.Setter;
 
 import java.util.Map;
 
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/Signature.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/Signature.java
index 972ba609344a025cc0b1c31eecccbcb2a716a52d..316d85bf0a75d107622cdeeae98dfbccfa510db5 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/Signature.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/Signature.java
@@ -3,12 +3,9 @@ package de.fitko.fitconnect.api.domain.model.metadata.data;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import de.fitko.fitconnect.api.domain.model.metadata.EidasAdesProfile;
 import de.fitko.fitconnect.api.domain.model.metadata.SignatureFormat;
 import lombok.Data;
-import lombok.Getter;
-import lombok.Setter;
 
 import java.util.Map;
 
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/SubmissionSchema.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/SubmissionSchema.java
index 42dff9ea9a83d8c8b4923cf1f001ddd74e26cf8e..05f8597545199bb3dc77bec0d71acfe5f727e22b 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/SubmissionSchema.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/metadata/data/SubmissionSchema.java
@@ -3,11 +3,8 @@ package de.fitko.fitconnect.api.domain.model.metadata.data;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import lombok.Data;
-import lombok.Getter;
 import lombok.NoArgsConstructor;
-import lombok.Setter;
 
 import java.net.URI;
 import java.util.Map;
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Callback.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Callback.java
index 4ba759951dde7da5133bc9b91c7ff9a98e448bbf..392aa49d5bd74f77108caf788676f9e442abec6d 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Callback.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Callback.java
@@ -2,9 +2,6 @@ package de.fitko.fitconnect.api.domain.model.submission;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.Data;
-import lombok.Getter;
-import lombok.Setter;
-import lombok.Value;
 
 import java.net.URI;
 
diff --git a/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Submission.java b/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Submission.java
index a82d214b234326ef1a3c8cc51a0a0e3696b11c42..39a47f9aacf4404b2a5f10d9c5518d0b0ce66c4a 100644
--- a/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Submission.java
+++ b/api/src/main/java/de/fitko/fitconnect/api/domain/model/submission/Submission.java
@@ -2,9 +2,7 @@ package de.fitko.fitconnect.api.domain.model.submission;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.Data;
-import lombok.Getter;
 import lombok.NoArgsConstructor;
-import lombok.Setter;
 
 import java.util.List;
 import java.util.UUID;
diff --git a/client/src/main/java/de/fitko/fitconnect/client/SenderClient.java b/client/src/main/java/de/fitko/fitconnect/client/SenderClient.java
index 897d70293bc7d955664767b8c7b6757f6ede168d..0092c2867883d54f2b94326ae1345200c3fce02e 100644
--- a/client/src/main/java/de/fitko/fitconnect/client/SenderClient.java
+++ b/client/src/main/java/de/fitko/fitconnect/client/SenderClient.java
@@ -347,18 +347,18 @@ public class SenderClient {
         }
 
         private ServiceType createServiceTypeWithDescription(final String name, final String description, final String leikaKey) {
-            final var serviceType = new ServiceType();
-            serviceType.setName(name);
-            serviceType.setDescription(description);
-            serviceType.setIdentifier(leikaKey);
-            return serviceType;
+            final var serviceTypeModel = new ServiceType();
+            serviceTypeModel.setName(name);
+            serviceTypeModel.setDescription(description);
+            serviceTypeModel.setIdentifier(leikaKey);
+            return serviceTypeModel;
         }
 
         private ServiceType createServiceTypeWithoutDescription(final String name, final String leikaKey) {
-            final var serviceType = new ServiceType();
-            serviceType.setName(name);
-            serviceType.setIdentifier(leikaKey);
-            return serviceType;
+            final var serviceTypeModel = new ServiceType();
+            serviceTypeModel.setName(name);
+            serviceTypeModel.setIdentifier(leikaKey);
+            return serviceTypeModel;
         }
 
         private Data createData(final DataPayload dataPayload) {
diff --git a/client/src/main/java/de/fitko/fitconnect/client/SubscriberClient.java b/client/src/main/java/de/fitko/fitconnect/client/SubscriberClient.java
index bcb18bea00d2d3dabf9bea6c7f0495886bd23b5d..03d92ba42a9997971c058ab5cb8df6fc02071267 100644
--- a/client/src/main/java/de/fitko/fitconnect/client/SubscriberClient.java
+++ b/client/src/main/java/de/fitko/fitconnect/client/SubscriberClient.java
@@ -155,7 +155,7 @@ public class SubscriberClient {
             } catch (final DecryptionException e) {
                 logger.error("Decrypting payload failed", e);
             } catch (final RestApiException e) {
-                logger.error("API request failed", submissionId, e);
+                logger.error("API request failed", e);
             } catch (final EventCreationException e) {
                 logger.error("Creating SET event failed", e);
             } catch (final InvalidSigningKeyException  e) {
diff --git a/client/src/main/java/de/fitko/fitconnect/client/cmd/CommandLineClient.java b/client/src/main/java/de/fitko/fitconnect/client/cmd/CommandLineClient.java
index 4b6c55d7cf0bbf98da33c5d41721afcc9f50cba9..aa8e36af5f9d142a1b04251e2d4c01dc986bdddd 100644
--- a/client/src/main/java/de/fitko/fitconnect/client/cmd/CommandLineClient.java
+++ b/client/src/main/java/de/fitko/fitconnect/client/cmd/CommandLineClient.java
@@ -85,7 +85,7 @@ public class CommandLineClient {
             jc.parse(args);
             return jc.getParsedCommand();
         } catch (final ParameterException e) {
-            logger.error(e.getMessage() + "\n");
+            logger.error(e.getMessage(), "\n");
             jc.usage();
             return null;
         }
@@ -131,12 +131,11 @@ public class CommandLineClient {
     private void writeData(final SubscriberClient.ReceivedSubmission submissionData, final String dataDirPath) throws IOException {
         logger.info("Creating data directory for submission in {}", dataDirPath);
         Files.createDirectories(Path.of(dataDirPath));
-        final String data = submissionData.getData();
 
         final var fileEnding = AttachmentDataType.getFileTypeFromMimeType(submissionData.getMimeType());
         final var filePath = Path.of(dataDirPath + "/data." + fileEnding);
         logger.info("Writing data.{}", fileEnding);
-        Files.write(filePath, data.getBytes(StandardCharsets.UTF_8));
+        Files.write(filePath, submissionData.getData().getBytes(StandardCharsets.UTF_8));
 
         for (final AttachmentWithData attachment : submissionData.getAttachments()) {
             final String filename = attachment.getAttachmentMetadata().getFilename();
diff --git a/client/src/main/java/de/fitko/fitconnect/client/factory/ApplicationConfigLoader.java b/client/src/main/java/de/fitko/fitconnect/client/factory/ApplicationConfigLoader.java
index ab336b5da0c110954ad5b522ceb3d02d40763a1e..ce7b0f3f6313918982f47f9249f67e58d942c40b 100644
--- a/client/src/main/java/de/fitko/fitconnect/client/factory/ApplicationConfigLoader.java
+++ b/client/src/main/java/de/fitko/fitconnect/client/factory/ApplicationConfigLoader.java
@@ -4,14 +4,14 @@ import de.fitko.fitconnect.api.config.ApplicationConfig;
 import org.yaml.snakeyaml.Yaml;
 import org.yaml.snakeyaml.constructor.Constructor;
 
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
 public class ApplicationConfigLoader {
 
+    private ApplicationConfigLoader(){}
+
     /**
      * Load ApplicationConfig from path.
      *
diff --git a/client/src/test/java/de/fitko/fitconnect/client/ClientIntegrationTest.java b/client/src/test/java/de/fitko/fitconnect/client/ClientIntegrationTest.java
index 3b12e19c3b0f303cf9c0e936cc9594b130a5c9d7..bc9c7cca898ff72fe79f5834bb6d23b7dc13ab91 100644
--- a/client/src/test/java/de/fitko/fitconnect/client/ClientIntegrationTest.java
+++ b/client/src/test/java/de/fitko/fitconnect/client/ClientIntegrationTest.java
@@ -19,14 +19,14 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 /**
  * This test uses real credentials and endpoints stored in gitlab ci variables to test the sdk against a real system
  */
-public class ClientIntegrationTest {
+class ClientIntegrationTest {
 
     final String authBaseUrl = "https://auth-testing.fit-connect.fitko.dev";
     final String submissionBaseUrl = "https://submission-api-testing.fit-connect.fitko.dev";
 
     @Test
     @EnabledIfEnvironmentVariable(named = "TEST_DESTINATION_ID", matches = ".*")
-    public void testSendAndConfirmCycle() {
+    void testSendAndConfirmCycle() {
 
         // Given
         final var testEnv = new Environment(authBaseUrl, submissionBaseUrl, true);
@@ -55,7 +55,7 @@ public class ClientIntegrationTest {
 
     @Test
     @EnabledIfEnvironmentVariable(named = "TEST_DESTINATION_ID", matches = ".*")
-    public void testListSubmissions() {
+    void testListSubmissions() {
 
         // Given
         final var testEnv = new Environment(authBaseUrl, submissionBaseUrl, true);
@@ -100,7 +100,7 @@ public class ClientIntegrationTest {
 
     @Test
     @EnabledIfEnvironmentVariable(named = "TEST_DESTINATION_ID", matches = ".*")
-    public void testAbortedSendSubmissionWithKeyValidationNotSilent() {
+    void testAbortedSendSubmissionWithKeyValidationNotSilent() {
 
         // Given
         final var prodEnv = new Environment(authBaseUrl, submissionBaseUrl, false);
diff --git a/client/src/test/java/de/fitko/fitconnect/client/SenderClientTest.java b/client/src/test/java/de/fitko/fitconnect/client/SenderClientTest.java
index c203eee55c58a6378e3793a912306ea32c1a207c..f2937f047812378a442c9aa38882816230e468e3 100644
--- a/client/src/test/java/de/fitko/fitconnect/client/SenderClientTest.java
+++ b/client/src/test/java/de/fitko/fitconnect/client/SenderClientTest.java
@@ -33,19 +33,17 @@ public class SenderClientTest {
 
     private Sender senderMock;
     private SenderClient.WithDestination underTest;
-    private Environment environmentMock;
 
     private final LogCaptor logs = new LogCaptor();
 
     @BeforeEach
     public void setup() {
-        senderMock = mock(Sender.class);
-        environmentMock = mock(Environment.class);
-        underTest = SenderClient.build(senderMock, "", environmentMock);
+        this.senderMock = mock(Sender.class);
+        this.underTest = SenderClient.build(senderMock, "", mock(Environment.class));
     }
 
     @Test
-    public void testSendSubmissionWithJsonData() throws Exception {
+    void testSendSubmissionWithJsonData() throws Exception {
 
         // Given
 
@@ -80,7 +78,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testSendSubmissionWithXmlData() throws Exception {
+    void testSendSubmissionWithXmlData() throws Exception {
 
         // Given
 
@@ -114,7 +112,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testMimeTypeDetection() throws Exception {
+    void testMimeTypeDetection() throws Exception {
 
         // Given
         final UUID destinationId = setupTestMocks();
@@ -137,7 +135,7 @@ public class SenderClientTest {
 
 
     @Test
-    public void testWithMissingData() throws Exception {
+    void testWithMissingData() throws Exception {
 
         // Given
         final UUID destinationId = setupTestMocks();
@@ -155,7 +153,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithMissingDestinationId() throws Exception {
+    void testWithMissingDestinationId() throws Exception {
 
         // Given
         setupTestMocks();
@@ -173,7 +171,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testMissingDataMimeTypeSchema() throws Exception {
+    void testMissingDataMimeTypeSchema() throws Exception {
 
         // Given
         final var destinationId = UUID.randomUUID();
@@ -201,7 +199,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithMissingServiceTypeName() throws Exception {
+    void testWithMissingServiceTypeName() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -219,7 +217,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithOptionalServiceTypeIdentifier() throws Exception {
+    void testWithOptionalServiceTypeIdentifier() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -237,7 +235,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithMissingServiceTypeDescription() throws Exception {
+    void testWithMissingServiceTypeDescription() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -254,7 +252,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithEmptyAttachments() throws Exception {
+    void testWithEmptyAttachments() throws Exception {
 
         // Given
         final UUID destinationId = setupTestMocks();
@@ -273,7 +271,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithAttachmentFileNull() throws Exception {
+    void testWithAttachmentFileNull() throws Exception {
 
         // Given
         final UUID destinationId = setupTestMocks();
@@ -292,7 +290,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testWithAttachmentPathNotPresent() throws Exception {
+    void testWithAttachmentPathNotPresent() throws Exception {
 
         // Given
         final UUID destinationId = setupTestMocks();
@@ -311,7 +309,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testInvalidPublicKey() throws Exception {
+    void testInvalidPublicKey() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -330,7 +328,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testEncryptionError() throws Exception {
+    void testEncryptionError() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -349,7 +347,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testAnnouncingSubmissionFailed() throws Exception {
+    void testAnnouncingSubmissionFailed() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -369,7 +367,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testRestApiCallFailed() throws Exception {
+    void testRestApiCallFailed() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -388,7 +386,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testGettingEncryptionKeyFailed() throws Exception {
+    void testGettingEncryptionKeyFailed() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
@@ -406,7 +404,7 @@ public class SenderClientTest {
     }
 
     @Test
-    public void testFailOnInvalidMetadata() throws Exception {
+    void testFailOnInvalidMetadata() throws Exception {
 
         // Given
         final var destinationId = setupTestMocks();
diff --git a/client/src/test/java/de/fitko/fitconnect/client/SubscriberClientTest.java b/client/src/test/java/de/fitko/fitconnect/client/SubscriberClientTest.java
index 8469c78a8a0bae4632c180dda3e7bb7514dff9b2..1be40888067031501ea05049497e4d96532725ee 100644
--- a/client/src/test/java/de/fitko/fitconnect/client/SubscriberClientTest.java
+++ b/client/src/test/java/de/fitko/fitconnect/client/SubscriberClientTest.java
@@ -34,7 +34,7 @@ import static org.junit.jupiter.api.Assertions.*;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.*;
 
-public class SubscriberClientTest {
+class SubscriberClientTest {
 
     public static final ObjectMapper mapper = new ObjectMapper();
 
@@ -53,13 +53,13 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testMissingPrivateKey() {
+    void testMissingPrivateKey() {
         assertNull(SubscriberClient.builder(subscriberMock, null, ""));
         logs.assertContains("No decryption key set, please check environment");
     }
 
     @Test
-    public void testPrivateKeyNotParseable() {
+    void testPrivateKeyNotParseable() {
         // Given
         final var client = SubscriberClient.builder(subscriberMock, "broken key", "");
 
@@ -73,13 +73,13 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testMissingMetadataSchema() {
+    void testMissingMetadataSchema() {
         assertNull(SubscriberClient.builder(subscriberMock, privateKey, null));
         logs.assertContains("No metadata schema present, please check environment");
     }
 
     @Test
-    public void testNoSubmissionsFound() {
+    void testNoSubmissionsFound() {
         assertThat(underTest.getAvailableSubmissions(null).isEmpty(), is(true));
         assertThat(underTest.getAvailableSubmissions(UUID.randomUUID()).isEmpty(), is(true));
 
@@ -89,7 +89,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testRestCallFailed() {
+    void testRestCallFailed() {
         // Given
         when(subscriberMock.getSubmission(any())).thenThrow(new RestApiException("Submission not found"));
 
@@ -102,7 +102,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testDecryptionFailed() {
+    void testDecryptionFailed() {
         // Given
         final var submissionId = UUID.randomUUID();
         final var submission = new Submission();
@@ -122,7 +122,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testCreatingSetEventFailed() throws JsonProcessingException {
+    void testCreatingSetEventFailed() throws JsonProcessingException {
         // Given
         final var submissionId = UUID.randomUUID();
 
@@ -148,7 +148,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testSigningKeyInvalid() throws JsonProcessingException {
+    void testSigningKeyInvalid() throws JsonProcessingException {
         // Given
         final var submissionId = UUID.randomUUID();
 
@@ -176,7 +176,7 @@ public class SubscriberClientTest {
 
 
     @Test
-    public void testReadingMetadataFailed() {
+    void testReadingMetadataFailed() {
         // Given
         final var submissionId = UUID.randomUUID();
         final var submission = new Submission();
@@ -197,7 +197,7 @@ public class SubscriberClientTest {
 
 
     @Test
-    public void testSubmissionsFound() {
+    void testSubmissionsFound() {
         // Given
         final var destinationId = UUID.randomUUID();
 
@@ -216,7 +216,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testGetSubmission() throws Exception {
+    void testGetSubmission() throws Exception {
 
         // Given
         final var dataPayload = "{ some : 'data foo' }";
@@ -272,7 +272,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testSubmissionNotFound() {
+    void testSubmissionNotFound() {
         // Given
         when(subscriberMock.getSubmission(any())).thenReturn(null);
 
@@ -284,7 +284,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testInvalidMetadata() throws JsonProcessingException {
+    void testInvalidMetadata() throws JsonProcessingException {
         // Given
         final var submissionId = UUID.randomUUID();
         final var destinationId = UUID.randomUUID();
@@ -311,7 +311,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testCorruptedData() throws JsonProcessingException, ParseException {
+    void testCorruptedData() throws JsonProcessingException, ParseException {
         // Given
         final RSAKey decryptionKey = RSAKey.parse(privateKey);
         final RSAKey encryptionKey = decryptionKey.toPublicJWK();
@@ -360,7 +360,7 @@ public class SubscriberClientTest {
     }
 
     @Test
-    public void testCorruptedAttachment() throws JsonProcessingException, ParseException {
+    void testCorruptedAttachment() throws JsonProcessingException, ParseException {
         // Given
         final RSAKey decryptionKey = RSAKey.parse(privateKey);
         final RSAKey encryptionKey = decryptionKey.toPublicJWK();
diff --git a/client/src/test/java/de/fitko/fitconnect/client/factory/ClientFactoryTest.java b/client/src/test/java/de/fitko/fitconnect/client/factory/ClientFactoryTest.java
index c1be40f038f1296e5f441954343d02951ccf71cd..3e611a621cd4cf54ec4041afb19540a5b579f430 100644
--- a/client/src/test/java/de/fitko/fitconnect/client/factory/ClientFactoryTest.java
+++ b/client/src/test/java/de/fitko/fitconnect/client/factory/ClientFactoryTest.java
@@ -8,16 +8,16 @@ import java.util.Map;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-public class ClientFactoryTest {
+class ClientFactoryTest {
 
     @Test
-    public void testMissingConfiguration() {
+    void testMissingConfiguration() {
         assertThrows(IllegalStateException.class, () -> ClientFactory.senderClient());
         assertThrows(IllegalStateException.class, () -> ClientFactory.subscriberClient());
     }
 
     @Test
-    public void testSenderClientConstruction() {
+    void testSenderClientConstruction() {
 
         final var envName = new EnvironmentName("DEV");
         final var environments = Map.of(envName, new Environment("https://auth", "", true));
@@ -42,7 +42,7 @@ public class ClientFactoryTest {
     }
 
     @Test
-    public void testSubscriberClientConstruction() {
+    void testSubscriberClientConstruction() {
 
         final var envName = new EnvironmentName("DEV");
         final var environments = Map.of(envName, new Environment("https://auth", "", true));
diff --git a/core/src/main/java/de/fitko/fitconnect/core/auth/DefaultOAuthService.java b/core/src/main/java/de/fitko/fitconnect/core/auth/DefaultOAuthService.java
index 0d3ac1949d0645d38505877d82ac3d6a1a74b56e..08da79e454f564e3e2d51e410f3a1b79e4c02a93 100644
--- a/core/src/main/java/de/fitko/fitconnect/core/auth/DefaultOAuthService.java
+++ b/core/src/main/java/de/fitko/fitconnect/core/auth/DefaultOAuthService.java
@@ -72,15 +72,14 @@ public class DefaultOAuthService implements OAuthService {
         checkNotNull("tokenUrl", tokenUrl);
         final String requestBody = buildRequestBody(clientId, clientSecret);
         this.currentToken = performTokenRequest(requestBody);
-        this.tokenExpirationTime = LocalDateTime.now().plusSeconds(currentToken.getExpiresIn());
+        this.tokenExpirationTime = LocalDateTime.now().plusSeconds(this.currentToken.getExpiresIn());
     }
 
     private String buildRequestBody(final String clientId, final String clientSecret, final String... scope) {
-        final var data = new HashMap<String, String>() {{
-            put("grant_type", "client_credentials");
-            put("client_id", clientId);
-            put("client_secret", clientSecret);
-        }};
+        final var data = new HashMap<String, String>();
+        data.put("grant_type", "client_credentials");
+        data.put("client_id", clientId);
+        data.put("client_secret", clientSecret);
 
         if (scope.length > 0) {
             data.put("scope", String.join(",", scope));
diff --git a/core/src/main/java/de/fitko/fitconnect/core/crypto/HashService.java b/core/src/main/java/de/fitko/fitconnect/core/crypto/HashService.java
index 1cc1781d44206eae15c53ab622859732f6bc6d74..d8158b9fa6b4ab982bdf1f703084393b42994bda 100644
--- a/core/src/main/java/de/fitko/fitconnect/core/crypto/HashService.java
+++ b/core/src/main/java/de/fitko/fitconnect/core/crypto/HashService.java
@@ -38,7 +38,7 @@ public class HashService implements MessageDigestService {
 
     @Override
     public String toHexString(final byte[] hash) {
-        final StringBuffer hexStringBuffer = new StringBuffer();
+        final StringBuilder hexStringBuffer = new StringBuilder();
         for (int i = 0; i < hash.length; i++) {
             hexStringBuffer.append(byteToHex(hash[i]));
         }
diff --git a/core/src/main/java/de/fitko/fitconnect/core/events/SecurityEventTokenService.java b/core/src/main/java/de/fitko/fitconnect/core/events/SecurityEventTokenService.java
index 052f982bc8767a14ef4f96aba0f412f3a27974b5..e4264cf1db35bfc61f2c20d8bd54bdea99683b3f 100644
--- a/core/src/main/java/de/fitko/fitconnect/core/events/SecurityEventTokenService.java
+++ b/core/src/main/java/de/fitko/fitconnect/core/events/SecurityEventTokenService.java
@@ -6,7 +6,6 @@ import com.nimbusds.jose.JWSHeader;
 import com.nimbusds.jose.JWSSigner;
 import com.nimbusds.jose.crypto.RSASSASigner;
 import com.nimbusds.jose.jwk.JWK;
-import com.nimbusds.jose.jwk.KeyOperation;
 import com.nimbusds.jose.jwk.RSAKey;
 import com.nimbusds.jwt.JWTClaimsSet;
 import com.nimbusds.jwt.SignedJWT;
@@ -112,11 +111,11 @@ public class SecurityEventTokenService implements SecurityEventService {
         }
     }
 
-    public static void validateRSAKey(final RSAKey RSAKey){
-        validateTrueOrElseThrow(RSAKey.getModulus().decodeToBigInteger().bitLength() >= 4096, "JWK has wrong key length.");
-        validateTrueOrElseThrow(RSAKey.getAlgorithm().equals(JWSAlgorithm.PS512), "The specified public key does not use PS512 as algorithm.");
+    public static void validateRSAKey(final RSAKey rsaKey){
+        validateTrueOrElseThrow(rsaKey.getModulus().decodeToBigInteger().bitLength() >= 4096, "JWK has wrong key length.");
+        validateTrueOrElseThrow(rsaKey.getAlgorithm().equals(JWSAlgorithm.PS512), "The specified public key does not use PS512 as algorithm.");
         //validateTrueOrElseThrow(RSAKey.getKeyOperations().size() == 1 && RSAKey.getKeyOperations().contains(KeyOperation.VERIFY), "The specified public key is not intended for 'verify' as specified through key operation.");
-        validateTrueOrElseThrow(RSAKey.getPublicExponent().toString().equals("AQAB"), "The specified public key does not match the public exponent 'AQAB'.");
+        validateTrueOrElseThrow(rsaKey.getPublicExponent().toString().equals("AQAB"), "The specified public key does not match the public exponent 'AQAB'.");
 
     }
 
diff --git a/core/src/main/java/de/fitko/fitconnect/core/util/Preconditions.java b/core/src/main/java/de/fitko/fitconnect/core/util/Preconditions.java
index d809bc436f96d25cdbc81fdf93f115e7ffd5dc53..ea9677126646d63ea3951792dea69c7691caf419 100644
--- a/core/src/main/java/de/fitko/fitconnect/core/util/Preconditions.java
+++ b/core/src/main/java/de/fitko/fitconnect/core/util/Preconditions.java
@@ -4,14 +4,15 @@ import java.util.function.Supplier;
 
 public class Preconditions {
 
+    private Preconditions() {}
+
     /**
      * Throws a supplied (runtime) exception if the expression evaluates to false
      *
-     * @param argumentName name of the argument to check
      * @param expression expression to evaluate
      * @param exceptionSupplier supplier for the exception
      */
-    public static void checkArgument(final String argumentName, final boolean expression, final Supplier<? extends RuntimeException> exceptionSupplier) {
+    public static void checkArgument(final boolean expression, final Supplier<? extends RuntimeException> exceptionSupplier) {
         if (!expression) {
             throw exceptionSupplier.get();
         }
@@ -23,7 +24,7 @@ public class Preconditions {
      * @param expression expression to evaluate
      */
     public static void checkArgument(final String argumentName, final boolean expression) {
-       checkArgument(argumentName, expression, () -> new IllegalStateException("Parameter " + argumentName + " must not be null"));
+       checkArgument(expression, () -> new IllegalStateException("Parameter " + argumentName + " must not be null"));
     }
 
     /**
@@ -33,6 +34,6 @@ public class Preconditions {
      * @param argument argument to check
      */
     public static void checkNotNull(final String argumentName, final Object argument) {
-        checkArgument(argumentName, argument != null, () -> new IllegalStateException("Parameter " + argumentName + " must not be null"));
+        checkArgument(argument != null, () -> new IllegalStateException("Parameter " + argumentName + " must not be null"));
     }
 }
diff --git a/core/src/main/java/de/fitko/fitconnect/core/util/Strings.java b/core/src/main/java/de/fitko/fitconnect/core/util/Strings.java
index 22fce6c7c3a02e9fbc67ab5ce299690d076b52a9..4dd79e64189698b6b3f9597cf5753f6bf16316ff 100644
--- a/core/src/main/java/de/fitko/fitconnect/core/util/Strings.java
+++ b/core/src/main/java/de/fitko/fitconnect/core/util/Strings.java
@@ -2,6 +2,8 @@ package de.fitko.fitconnect.core.util;
 
 public class Strings {
 
+    private Strings() {}
+
     /**
      * Tests a given string on null or empty
      * @param s string to test
diff --git a/core/src/test/java/de/fitko/fitconnect/core/SubmissionSenderTestConfig.java b/core/src/test/java/de/fitko/fitconnect/core/SubmissionSenderTest.java
similarity index 90%
rename from core/src/test/java/de/fitko/fitconnect/core/SubmissionSenderTestConfig.java
rename to core/src/test/java/de/fitko/fitconnect/core/SubmissionSenderTest.java
index 4af26b5ae718898141508e9c2354ed39554989bf..325d36871f1a3ce190b2152480f9dd67a42f47e9 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/SubmissionSenderTestConfig.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/SubmissionSenderTest.java
@@ -7,11 +7,7 @@ import com.nimbusds.jose.jwk.RSAKey;
 import com.nimbusds.jose.jwk.gen.RSAKeyGenerator;
 import de.fitko.fitconnect.api.domain.model.destination.Destination;
 import de.fitko.fitconnect.api.domain.model.jwk.JWK;
-import de.fitko.fitconnect.api.domain.model.metadata.ContentStructure;
 import de.fitko.fitconnect.api.domain.model.metadata.Metadata;
-import de.fitko.fitconnect.api.domain.model.metadata.PublicServiceType;
-import de.fitko.fitconnect.api.domain.model.metadata.attachment.Attachment;
-import de.fitko.fitconnect.api.domain.model.metadata.data.*;
 import de.fitko.fitconnect.api.domain.model.submission.*;
 import de.fitko.fitconnect.api.domain.validation.ValidationResult;
 import de.fitko.fitconnect.api.exceptions.*;
@@ -26,10 +22,8 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import java.io.IOException;
-import java.net.URI;
 import java.text.ParseException;
 import java.util.Collections;
-import java.util.List;
 import java.util.UUID;
 
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -39,7 +33,7 @@ import static org.junit.jupiter.api.Assertions.*;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.*;
 
-public class SubmissionSenderTestConfig {
+class SubmissionSenderTest {
 
     private DestinationService destinationServiceMock;
     private SubmissionService submissionServiceMock;
@@ -70,7 +64,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void validatePublicKey() throws JOSEException {
+    void validatePublicKey() throws JOSEException {
 
         //Given
         final RSAKey publicKey = new RSAKeyGenerator(2048)
@@ -89,7 +83,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void encryptBytes() throws JOSEException {
+    void encryptBytes() throws JOSEException {
 
         //Given
         final RSAKey publicKey = new RSAKeyGenerator(2048)
@@ -109,7 +103,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void createHash() {
+    void createHash() {
 
         // Given
         when(cryptoServiceMock.hashBytes(any())).thenReturn("hashedData");
@@ -123,7 +117,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void createSubmission() {
+    void createSubmission() {
 
         // Given
         final var createSubmission = CreateSubmission.builder()
@@ -148,7 +142,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void uploadAttachment() {
+    void uploadAttachment() {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -165,7 +159,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void getEncryptionKeyForDestination() throws ParseException, IOException {
+    void getEncryptionKeyForDestination() throws ParseException, IOException {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -184,7 +178,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void getEncryptionKeyForDestinationFailed() {
+    void getEncryptionKeyForDestinationFailed() {
 
         // Given
         when(destinationServiceMock.getEncryptionKey(any(), any())).thenThrow(RestApiException.class);
@@ -199,7 +193,7 @@ public class SubmissionSenderTestConfig {
 
 
     @Test
-    public void encryptObject() throws JOSEException {
+    void encryptObject() throws JOSEException {
 
         //Given
         final RSAKey publicKey = new RSAKeyGenerator(2048)
@@ -220,7 +214,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void encryptingObjectFailed() throws JOSEException {
+    void encryptingObjectFailed() throws JOSEException {
 
         //Given
         final RSAKey publicKey = new RSAKeyGenerator(2048)
@@ -241,7 +235,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void sendSubmission() {
+    void sendSubmission() {
 
         // Given
         final SubmitSubmission submitSubmission = new SubmitSubmission();
@@ -264,7 +258,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void getDestination() {
+    void getDestination() {
 
         // Given
         final var destinationId = UUID.randomUUID();
@@ -282,7 +276,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void testValidMetadata() {
+    void testValidMetadata() {
 
         // Given
         final var metadata = new Metadata();
@@ -297,7 +291,7 @@ public class SubmissionSenderTestConfig {
     }
 
     @Test
-    public void testInvalidMetadata() {
+    void testInvalidMetadata() {
 
         // Given
         final var invalidMetadata = new Metadata();
@@ -313,6 +307,6 @@ public class SubmissionSenderTestConfig {
     }
 
     private String getResourceAsString(final String filename) throws IOException {
-        return new String(SubmissionSenderTestConfig.class.getResourceAsStream(filename).readAllBytes());
+        return new String(SubmissionSenderTest.class.getResourceAsStream(filename).readAllBytes());
     }
 }
\ No newline at end of file
diff --git a/core/src/test/java/de/fitko/fitconnect/core/SubmissionSubscriberTest.java b/core/src/test/java/de/fitko/fitconnect/core/SubmissionSubscriberTest.java
index c91a6ae26db0c44b1e887ce637864163822105bd..82ea0cd304239bd0ec05f4da407f7fb621f4bbf6 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/SubmissionSubscriberTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/SubmissionSubscriberTest.java
@@ -32,7 +32,7 @@ import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.*;
 
-public class SubmissionSubscriberTest {
+class SubmissionSubscriberTest {
 
     private SubmissionService submissionServiceMock;
     private EventLogService eventLogServiceMock;
@@ -61,7 +61,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void decryptStringContent() throws JOSEException {
+    void decryptStringContent() throws JOSEException {
 
         // Given
         final RSAKey privateKey = new RSAKeyGenerator(2048)
@@ -81,7 +81,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void pollAvailableSubmissions() {
+    void pollAvailableSubmissions() {
 
         // Given
         final var destinationId = UUID.randomUUID();
@@ -101,7 +101,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void getSubmission() {
+    void getSubmission() {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -120,7 +120,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void submissionNotFound() {
+    void submissionNotFound() {
 
         // Given
         when(submissionServiceMock.getSubmission(any())).thenThrow(RestApiException.class);
@@ -134,7 +134,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void fetchAttachment() {
+    void fetchAttachment() {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -150,13 +150,8 @@ public class SubmissionSubscriberTest {
         assertThat(encryptedAttachment, equalTo(expectedAttachment));
     }
 
-    @Disabled("Needs proper impl first")
-    void validateEventLog() {
-
-    }
-
     @Test
-    public void validateMetadata() {
+    void validateMetadata() {
 
         // Given
         when(validationServiceMock.validateMetadataSchema(any(), any())).thenReturn(ValidationResult.ok());
@@ -169,7 +164,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void invalidMetadata() {
+    void invalidMetadata() {
 
         // Given
         when(validationServiceMock.validateMetadataSchema(any(), any())).thenReturn(ValidationResult.error(new Exception("Failed parsing metadata")));
@@ -183,7 +178,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void validateHashIntegrity() {
+    void validateHashIntegrity() {
 
         when(validationServiceMock.validateIntegrity(any(),any())).thenReturn(ValidationResult.ok());
 
@@ -195,7 +190,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void validateCorruptHash() {
+    void validateCorruptHash() {
 
         // Given
         when(validationServiceMock.validateIntegrity(any(),any())).thenReturn(ValidationResult.error(
@@ -210,7 +205,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void confirmValidSubmission() {
+    void confirmValidSubmission() {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -229,7 +224,7 @@ public class SubmissionSubscriberTest {
     }
 
     @Test
-    public void rejectSubmission() {
+    void rejectSubmission() {
 
         // Given
         final var submissionId = UUID.randomUUID();
diff --git a/core/src/test/java/de/fitko/fitconnect/core/auth/DefaultOAuthServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/auth/DefaultOAuthServiceTest.java
index d03efddf86c45505da194ccc07d8434531c0e450..c2762e957dab165670e564b8a07f86cf40decce4 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/auth/DefaultOAuthServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/auth/DefaultOAuthServiceTest.java
@@ -15,7 +15,7 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-public class DefaultOAuthServiceTest extends RestEndpointBase {
+class DefaultOAuthServiceTest extends RestEndpointBase {
 
     private OAuthService underTest;
 
@@ -27,7 +27,7 @@ public class DefaultOAuthServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void serviceNotInitialized() {
+    void serviceNotInitialized() {
         // Given
         final OAuthService instance =  new DefaultOAuthService(null, null, null, null);
 
@@ -40,7 +40,7 @@ public class DefaultOAuthServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void getCurrentToken() throws JsonProcessingException {
+    void getCurrentToken() throws JsonProcessingException {
         // Given
         final OAuthToken token= new OAuthToken();
         token.setAccessToken("123");
@@ -57,7 +57,7 @@ public class DefaultOAuthServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void refreshTokenWhenExpired() throws JsonProcessingException {
+    void refreshTokenWhenExpired() throws JsonProcessingException {
         // Given
         final OAuthToken oldToken = new OAuthToken();
         oldToken.setAccessToken("123");
diff --git a/core/src/test/java/de/fitko/fitconnect/core/auth/OAuthTokenIntegrationTest.java b/core/src/test/java/de/fitko/fitconnect/core/auth/OAuthTokenIntegrationTest.java
index ac888e38ba10e751f2fd6ca15aa5ea114c4e7844..5a165a999c861f6f78d81d06aca42ec0496da590 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/auth/OAuthTokenIntegrationTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/auth/OAuthTokenIntegrationTest.java
@@ -6,10 +6,10 @@ import org.springframework.web.client.RestTemplate;
 
 import static org.junit.jupiter.api.Assertions.*;
 
-public class OAuthTokenIntegrationTest {
+class OAuthTokenIntegrationTest {
 
     @Test
-    public void retrieveAuthenticationToken() {
+    void retrieveAuthenticationToken() {
 
         // Given
         final var tokenUrl = "https://auth-testing.fit-connect.fitko.dev/token";
diff --git a/core/src/test/java/de/fitko/fitconnect/core/crypto/HashServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/crypto/HashServiceTest.java
index d0a4b1f05a7d060d378c6808662bf6f33e0bd92f..4b4074956b462acecf12bf18d845afa78ad779fc 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/crypto/HashServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/crypto/HashServiceTest.java
@@ -14,7 +14,7 @@ import static org.hamcrest.Matchers.equalTo;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-public class HashServiceTest {
+class HashServiceTest {
 
     private MessageDigestService underTest;
 
@@ -25,7 +25,7 @@ public class HashServiceTest {
     }
 
     @Test
-    public void createHash() throws IOException {
+    void createHash() throws IOException {
 
         // Given
         final byte[] expectedHash = {-13, -77, -85, 62, 99, 81, -30, 91, 92, 24, -126, -66, -88, -45, 126, -6, -35,
@@ -43,7 +43,7 @@ public class HashServiceTest {
     }
 
     @Test
-    public void verify() throws IOException {
+    void verify() throws IOException {
         // Given
         final byte[] expectedHash = {-13, -77, -85, 62, 99, 81, -30, 91, 92, 24, -126, -66, -88, -45, 126, -6, -35,
                 -64, -22, 114, -65, 21, 59, -80, 103, 104, -113, 119, 90, 38, -127, 13, 50, -75, 79, 1, 75, -15, -50,
@@ -60,7 +60,7 @@ public class HashServiceTest {
     }
 
     @Test
-    public  void toHexString() {
+    void toHexString() {
         // Given
         final byte[] data = "some data".getBytes(StandardCharsets.UTF_8);
         final var expectedHexString = "736f6d652064617461";
@@ -73,7 +73,7 @@ public class HashServiceTest {
     }
 
     @Test
-    public void fromHexString() {
+    void fromHexString() {
         // Given
         final var hexString = "736f6d652064617461";
 
diff --git a/core/src/test/java/de/fitko/fitconnect/core/destination/DestinationRestServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/destination/DestinationRestServiceTest.java
index 4a76c517e35e5bcf3ad035e46ce2264f0490a0cc..a273da99a952b3f7f6084f81d3153cda9036ccda 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/destination/DestinationRestServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/destination/DestinationRestServiceTest.java
@@ -21,7 +21,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
-public class DestinationRestServiceTest extends RestEndpointBase {
+class DestinationRestServiceTest extends RestEndpointBase {
 
     DestinationService underTest;
     OAuthService authServiceMock;
@@ -34,7 +34,7 @@ public class DestinationRestServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void getDestination() throws JsonProcessingException {
+    void getDestination() throws JsonProcessingException {
 
         //Given
         final Destination expectedDestination = new Destination();
@@ -57,7 +57,7 @@ public class DestinationRestServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void getEncryptionKey() throws Exception {
+    void getEncryptionKey() throws Exception {
         // Given
         final UUID destinationId = UUID.randomUUID();
         final JWK jwk = new JWK();
diff --git a/core/src/test/java/de/fitko/fitconnect/core/events/EventLogApiServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/events/EventLogApiServiceTest.java
index 039e1f2142b66ec6195960264d090ccabd37545a..f78967a06844e8344642f60c85957206c6ce676a 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/events/EventLogApiServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/events/EventLogApiServiceTest.java
@@ -24,7 +24,7 @@ import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.when;
 
-public class EventLogApiServiceTest extends RestEndpointBase {
+class EventLogApiServiceTest extends RestEndpointBase {
 
     EventLogService underTest;
     OAuthService authServiceMock;
@@ -37,7 +37,7 @@ public class EventLogApiServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void getEventLog() throws JsonProcessingException {
+    void getEventLog() throws JsonProcessingException {
         // Given
         final var caseId = UUID.randomUUID();
 
@@ -54,7 +54,7 @@ public class EventLogApiServiceTest extends RestEndpointBase {
                 "    }";
 
         final var expectedLog = new EventLog();
-        expectedLog.setEventLog(List.of(sampleLog));
+        expectedLog.setEventLogs(List.of(sampleLog));
 
         final var authToken = new OAuthToken();
         authToken.setAccessToken("abc");
@@ -74,7 +74,7 @@ public class EventLogApiServiceTest extends RestEndpointBase {
         final EventLog log = underTest.getEventLog(caseId);
 
         // Then
-        final List<String> eventLog = log.getEventLog();
+        final List<String> eventLog = log.getEventLogs();
         assertFalse(eventLog.isEmpty());
         assertTrue(eventLog.stream().findFirst().isPresent());
         assertThat(eventLog.stream().findFirst().get(), is(sampleLog));
@@ -82,7 +82,7 @@ public class EventLogApiServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void sendEvent() {
+    void sendEvent() {
         // Given
         final var caseId = UUID.randomUUID();
         final var serialisedSetEvent = "eyJraWQiOiJkZDA0MDllNS00MTBlLTRkOTgtODViNi1mODFhNDBiO";
diff --git a/core/src/test/java/de/fitko/fitconnect/core/events/SecurityEventTokenServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/events/SecurityEventTokenServiceTest.java
index 351882317035e9b902cea6cf19f9ca15ab194abe..2b302cfd2c9739646d124501aa8162d265014d86 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/events/SecurityEventTokenServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/events/SecurityEventTokenServiceTest.java
@@ -23,7 +23,7 @@ import java.util.UUID;
 
 import static org.junit.jupiter.api.Assertions.*;
 
-public class SecurityEventTokenServiceTest {
+class SecurityEventTokenServiceTest {
 
     String signingKey;
     SecurityEventService underTest;
@@ -37,7 +37,7 @@ public class SecurityEventTokenServiceTest {
     }
 
     @Test
-    public void createAcceptSubmissionEvent() throws ParseException, JOSEException {
+    void createAcceptSubmissionEvent() throws ParseException, JOSEException {
 
         final String event = underTest.createAcceptSubmissionEvent(UUID.randomUUID(), UUID.randomUUID(), UUID.randomUUID());
 
@@ -49,13 +49,13 @@ public class SecurityEventTokenServiceTest {
         final Map<String,Object> obj = (Map<String, Object>) payload.getClaims().get("events");
         final Optional<String> first = obj.keySet().stream().findFirst();
 
-        assertEquals(jwk.getAlgorithm(), JWSAlgorithm.PS512);
+        assertEquals(JWSAlgorithm.PS512, jwk.getAlgorithm());
         assertTrue(signedJWT.verify(jwsVerifier));
         assertEquals(SecurityEventTokenService.ACCEPT_EVENT, first.get());
     }
 
     @Test
-    public void createRejectSubmissionEvent() throws ParseException, JOSEException {
+    void createRejectSubmissionEvent() throws ParseException, JOSEException {
 
         // Given
         final String event = underTest.createRejectSubmissionEvent(UUID.randomUUID(), UUID.randomUUID(), UUID.randomUUID());
@@ -68,7 +68,7 @@ public class SecurityEventTokenServiceTest {
         assertEquals("secevent+jwt", header.getType().getType());
         assertEquals("PS512", header.getAlgorithm().getName());
         assertEquals(jwk.getKeyID(), header.getKeyID());
-        assertEquals(jwk.getAlgorithm(), JWSAlgorithm.PS512);
+        assertEquals(JWSAlgorithm.PS512, jwk.getAlgorithm());
 
         final JWTClaimsSet payload = signedJWT.getJWTClaimsSet();
         final Map<String,Object> obj = (Map<String, Object>) payload.getClaims().get("events");
@@ -80,7 +80,7 @@ public class SecurityEventTokenServiceTest {
     }
 
     @Test
-    public void signingKeyCannotBeParsed(){
+    void signingKeyCannotBeParsed(){
         assertThrows(
                 InvalidSigningKeyException.class,
                 () -> new SecurityEventTokenService("broken key"),
diff --git a/core/src/test/java/de/fitko/fitconnect/core/http/ProxyConfigTest.java b/core/src/test/java/de/fitko/fitconnect/core/http/ProxyConfigTest.java
index 1fb77d5da7e20a1b4c22224fa59bc21aa692cdc2..aef00310e7bca58d13a1169f7ecc75e74332c6b0 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/http/ProxyConfigTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/http/ProxyConfigTest.java
@@ -8,12 +8,12 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.equalTo;
 import static org.junit.jupiter.api.Assertions.*;
 
-public class ProxyConfigTest {
+class ProxyConfigTest {
 
     ProxyConfig underTest;
 
     @Test
-    public void proxyRestTemplate() {
+    void proxyRestTemplate() {
         // Given
         underTest = new ProxyConfig("http://testhost.de", 8080);
 
@@ -27,7 +27,7 @@ public class ProxyConfigTest {
     }
 
     @Test
-    public void hasProxySet() {
+    void hasProxySet() {
         // Given
         underTest = new ProxyConfig("http://testhost.de", 8080);
 
@@ -39,7 +39,7 @@ public class ProxyConfigTest {
     }
 
     @Test
-    public void hasProxyNotSet() {
+    void hasProxyNotSet() {
         // Given
         underTest = new ProxyConfig(null, 0);
 
@@ -51,7 +51,7 @@ public class ProxyConfigTest {
     }
 
     @Test
-    public void testToString() {
+    void testToString() {
         // Given
         underTest = new ProxyConfig("http://testhost.de", 8080);
 
diff --git a/core/src/test/java/de/fitko/fitconnect/core/submission/SubmissionApiServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/submission/SubmissionApiServiceTest.java
index da627ed22e14855936889ffff40385382a1fdf9e..9f97fe41bc86ccaa9c8db32a961db74ee19c30e5 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/submission/SubmissionApiServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/submission/SubmissionApiServiceTest.java
@@ -25,11 +25,10 @@ import java.util.stream.Collectors;
 import static com.github.tomakehurst.wiremock.client.WireMock.*;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.*;
 import static org.mockito.Mockito.when;
 
-public class SubmissionApiServiceTest extends RestEndpointBase {
+class SubmissionApiServiceTest extends RestEndpointBase {
 
     private RestTemplate restTemplate;
     private OAuthService authServiceMock;
@@ -47,7 +46,7 @@ public class SubmissionApiServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void announceSubmission() throws JsonProcessingException {
+    void announceSubmission() throws JsonProcessingException {
         // Given
         final var caseId = UUID.randomUUID();
         final var destinationId = UUID.randomUUID();
@@ -92,7 +91,7 @@ public class SubmissionApiServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void uploadAttachment() {
+    void uploadAttachment() {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -120,11 +119,11 @@ public class SubmissionApiServiceTest extends RestEndpointBase {
         // Then
         verify(putRequestedFor(urlEqualTo(urlPath)).withHeader("Authorization", equalTo("Bearer abc")));
         assertThat(response.getHeaders().getContentTypeHeader().mimeTypePart(), is("application/jose"));
-        assertTrue(response.getStatus() == HttpStatus.NO_CONTENT.value());
+        assertEquals(response.getStatus(), HttpStatus.NO_CONTENT.value());
     }
 
     @Test
-    public void getAttachment() {
+    void getAttachment() {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -153,11 +152,11 @@ public class SubmissionApiServiceTest extends RestEndpointBase {
         assertThat(attachment, is(encryptedAttachment));
         verify(getRequestedFor(urlEqualTo(urlPath)).withHeader("Authorization", equalTo("Bearer abc")));
         assertThat(response.getHeaders().getContentTypeHeader().mimeTypePart(), is("application/jose"));
-        assertTrue(response.getStatus() == HttpStatus.OK.value());
+        assertEquals(response.getStatus(), HttpStatus.OK.value());
     }
 
     @Test
-    public void sendSubmission() throws JsonProcessingException {
+    void sendSubmission() throws JsonProcessingException {
 
         // Given
         final var submissionId = UUID.randomUUID();
@@ -200,11 +199,11 @@ public class SubmissionApiServiceTest extends RestEndpointBase {
 
         verify(putRequestedFor(urlEqualTo(urlPath)).withHeader("Authorization", equalTo("Bearer abc")));
         assertThat(response.getHeaders().getContentTypeHeader().mimeTypePart(), is("application/json"));
-        assertTrue(response.getStatus() == HttpStatus.OK.value());
+        assertEquals(response.getStatus(), HttpStatus.OK.value());
     }
 
     @Test
-    public void pollAvailableSubmissions() throws JsonProcessingException {
+    void pollAvailableSubmissions() throws JsonProcessingException {
 
         final int offset = 0;
         final int limit = 10;
@@ -248,7 +247,7 @@ public class SubmissionApiServiceTest extends RestEndpointBase {
     }
 
     @Test
-    public void getSubmission() throws JsonProcessingException {
+    void getSubmission() throws JsonProcessingException {
         // Given
         final var submissionId = UUID.randomUUID();
 
diff --git a/core/src/test/java/de/fitko/fitconnect/core/util/StringsTest.java b/core/src/test/java/de/fitko/fitconnect/core/util/StringsTest.java
index b73765ebe414e71597506eac42c453d610a3ea43..adc4a413b74387f5420c2d8172dedf586e105db6 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/util/StringsTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/util/StringsTest.java
@@ -4,10 +4,10 @@ import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
 
-public class StringsTest {
+class StringsTest {
 
     @Test
-    public void isEmpty() {
+    void isEmpty() {
         
         // Given
         final var emptyString = "";
@@ -20,7 +20,7 @@ public class StringsTest {
     }
 
     @Test
-    public void isNUll() {
+    void isNUll() {
 
         // Given
         final String nullString = null;
diff --git a/core/src/test/java/de/fitko/fitconnect/core/validation/DefaultValidationServiceTest.java b/core/src/test/java/de/fitko/fitconnect/core/validation/DefaultValidationServiceTest.java
index 81547def95fdae87751fd5a2b14c7a2b89023040..84158b25b894ad885e521d2b1d7797424b42cb38 100644
--- a/core/src/test/java/de/fitko/fitconnect/core/validation/DefaultValidationServiceTest.java
+++ b/core/src/test/java/de/fitko/fitconnect/core/validation/DefaultValidationServiceTest.java
@@ -30,7 +30,7 @@ import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-public class DefaultValidationServiceTest {
+class DefaultValidationServiceTest {
 
     private ValidationService underTest;
     private MessageDigestService hashService;
@@ -46,7 +46,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void testValidKeyWithoutX509CertChain() throws JOSEException {
+    void testValidKeyWithoutX509CertChain() throws JOSEException {
 
         //Given
         final RSAKey rsaKey = new RSAKeyGenerator(4096)
@@ -63,7 +63,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void testInvalidKeyWithWrongAlgorithm() throws JOSEException {
+    void testInvalidKeyWithWrongAlgorithm() throws JOSEException {
 
         //Given
         final RSAKey rsaKey = new RSAKeyGenerator(4096)
@@ -82,7 +82,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void testValidationWithProxy() {
+    void testValidationWithProxy() {
 
         //Given
         final var config = ApplicationConfig.builder()
@@ -103,7 +103,7 @@ public class DefaultValidationServiceTest {
 
 
     @Test
-    public void validateMetadata() throws IOException {
+    void validateMetadata() throws IOException {
 
         // Given
         final var submissionSchema = new SubmissionSchema();
@@ -135,7 +135,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void validateMetadataWithMissingProperties() throws IOException {
+    void validateMetadataWithMissingProperties() throws IOException {
 
         // Given
         final var submissionSchema = new SubmissionSchema();
@@ -163,7 +163,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void validateMetadataWithInvalidPattern() throws IOException {
+    void validateMetadataWithInvalidPattern() throws IOException {
 
         // Given
         final var submissionSchema = new SubmissionSchema();
@@ -196,7 +196,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void validateMatchingHash() {
+    void validateMatchingHash() {
 
         // Given
         final var hexHashFromSender = hashService.toHexString(hashService.createHash("some data".getBytes()));
@@ -209,7 +209,7 @@ public class DefaultValidationServiceTest {
     }
 
     @Test
-    public void validateCorruptHash() {
+    void validateCorruptHash() {
 
         // Given
         final var hexHashFromSender = "e1645e7492f032fb62c674db75500be7b260bfc0daa965821ddb3f8a49b5d33788ee3f04";