Resolve "Prepare and implement initial feedback"

Related issues

"Related to #3 (closed) "

Acceptance criteria

• Implemented code changes don't diverge from the related issue.
• Documentation reflects the status quo after merge.
• Version number is incremented according to SemVer. (Snapshot versions are not merged/released.)
• Only released versions of dependencies are used (i.e. no snapshot versions).
• Pipeline still works.
• GitLab issue is up-to-date.

If necessary, the following sections have been updated:

• Readme.md
• Documentation

Proposed squash commit message

Updated ecmr data model based on working group Feedback

• Version increase to 0.2.0
• Remove all @NotNUll constraints except for eCMRId in ECMRData
• All changes are listed within CHANGELOG.md in root directory of the project.

Co-authored-by: Björn Krämer bjoern.kraemer@iml.fraunhofer.de

Co-authored-by: Marcus Schroer marcus.schroeer@iml.fraunhofer.de

Co-authored-by: Niklas Burczyk niklas.burczyk@iml.fraunhofer.de