DINC0500664 : Multi level entity fix

[rishikunnath2747]

This PR fixes the issue where Save handler and Link related methods weren't working if the attachments aspect wasn't a direct composition on the Root entity, but rather a nested entity inside the Root entity

Leading application changes PR (Develop deploy) : #339
Leading application changes PR (Local deploy) : #340

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist before requesting a review

• I follow Java Development Guidelines for SAP
• I have tested the functionality on my cloud environment.
• I have provided sufficient automated/ unit tests for the code.
• I have increased or maintained the test coverage.
• I have ran integration tests on my cloud environment.
• I have validated blackduck portal for any vulnerability after my commit.

Integration tests

Multitenancy job : https://github.com/cap-java/sdm/actions/runs/18743590582/job/53465517478

1. Single Tenant : https://github.com/cap-java/sdm/actions/runs/18742931813/job/53463365579
2. Multi Tenant (Tenant 1) (Named User)

3. Multi Tenant (Tenant 1) (Technical User)

4. Multi Tenant (Tenant 2) (Named User)

5. Multi Tenant (Tenant 2) (Technical User)