fix: Response body for post

[VivekHub97]

fix: Response body for posting in submodel repository and submodel service

Closes #398
Closes #457

[mdanish98]

Hi @VivekHub97 ,

Thanks a lot for the implementation.

Actually, this should be fixed in core [1] and [2] first and then at the Controller side, the return type here in [1] and [2] is void but it should be SubmodelElement, and then at the HttpController [3] and [4] respectively for Repo and Service, it should be like below:

@Override
public ResponseEntity<SubmodelElement> postSubmodelElementSubmodelRepo(Base64UrlEncodedIdentifier submodelIdentifier, @Valid SubmodelElement body) {
    SubmodelElement createdSME = repository.createSubmodelElement(submodelIdentifier.getIdentifier(), body);
    return new ResponseEntity<SubmodelElement>(createdSME, HttpStatus.CREATED);
}

Inside SubmodelRepoHttpController [3] the method postSubmodelElementByPathSubmodelRepo is not fixed.

Following is the summary:

• Update interfaces of SubmodelRepository [1] and SubmodelService [2] for createSubmodelElement methods (there are multiple overloaded methods) such that the return type is SME instead of void.
• Then handle this appropriately wherever these interfaces are implemented possibly in all implementations (Crud*Repo) and all features.
• Update HTTP controllers for SMRepo [3] and SMService [4] like I defined above
• Update the test cases to additionally check the creation response wherever required. (Maybe do this first to achieve Test Driven Development).

[1] basyx-java-server-sdk/basyx.submodelrepository/basyx.submodelrepository-core/src/main/java/org/eclipse/digitaltwin/basyx/submodelrepository/SubmodelRepository.java at main · eclipse-basyx/basyx-java-server-sdk (github.com)
[2] basyx-java-server-sdk/basyx.submodelservice/basyx.submodelservice-core/src/main/java/org/eclipse/digitaltwin/basyx/submodelservice/SubmodelService.java at main · eclipse-basyx/basyx-java-server-sdk (github.com)
[3] basyx-java-server-sdk/basyx.submodelrepository/basyx.submodelrepository-http/src/main/java/org/eclipse/digitaltwin/basyx/submodelrepository/http/SubmodelRepositoryApiHTTPController.java at main · eclipse-basyx/basyx-java-server-sdk (github.com)
[4] basyx-java-server-sdk/basyx.submodelservice/basyx.submodelservice-http/src/main/java/org/eclipse/digitaltwin/basyx/submodelservice/http/SubmodelServiceHTTPApiController.java at main · eclipse-basyx/basyx-java-server-sdk (github.com)

[mdanish98]

There are no tests in the SubmodelServiceSuite. Please add them as well.