refactor: fix merge issues (planning#1243)

api/pom.xml

...dev/fitko/fitconnect/api/domain/sender/ReceivedReply.java

...dev/fitko/fitconnect/api/domain/sender/SendableReply.java

...itko/fitconnect/api/domain/sender/SendableSubmission.java

...main/sender/steps/unencrypted/OptionalPropertiesStep.java

...o/fitconnect/api/domain/subscriber/ReceivedReplyData.java

.../fitconnect/api/domain/subscriber/ReceivedSubmission.java

...connect/api/domain/subscriber/ReceivedSubmissionData.java

...ava/dev/fitko/fitconnect/client/sender/ReplyReceiver.java

.../dev/fitko/fitconnect/client/sender/SubmissionSender.java

...ient/sender/steps/unencrypted/OptionalPropertiesStep.java

...t/client/sender/strategies/SendNewSubmissionStrategy.java

...a/dev/fitko/fitconnect/client/subscriber/ReplySender.java

...itko/fitconnect/client/subscriber/SubmissionReceiver.java

...connect/core/validation/DefaultValidationServiceTest.java