Jtikekar/reverting nullables

[juileetikekar]

Description

Upgrading the AAS Repo APIs to BugFix Version 3.0.2 and fixing the broken Get APIs.

Motivation and Context

Due to refactoring lot of APIs have stopped working. Thus, fixing the API step by step also upgrading the APIs to the latest BugFix Version.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

The APIs have been tested manually and with the aas-test-engine.

Screenshots (if appropriate):

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works

[CLAassistant]

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1 out of 2 committers have signed the CLA.

:white_check_mark: juileetikekar
:x: martafullen
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[martafullen]

Added copyright headers.
Note that this branch still contains OPCFoundation dependencies (and so does main), see PR #352