fix(OPENFRAM-010-6): CU-86akeeczr TagAssignment.entityType/entityId relationship undocumented despite non-obvious polymorphic semantics

[flamingo]

Closes findings from rule OPENFRAM-010-6 — TagAssignment.entityType/entityId relationship undocumented despite non-obvious polymorphic semantics.

Draft — this is a starting point, not a finished change. The fix required judgment, so read it before trusting it.

#	Fix confidence	Finding	Location
1	🟡 70 medium	TagAssignment.entityType/entityId relationship undocumented despite non-obvious polymorphic semantics	openframe-data-mongo-common/src/main/java/com/openframe/data/document/tag/TagAssignment.java:22

What changed — and what was deliberately left — is explained per finding as inline review comments on the lines each finding touched.

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Run: https://product-hub.flamingo.so/admin/code-review
Run id: 4f0d6344-55d4-49de-bc86-cac2510f432f

Merging this PR is recorded as acceptance of the rule that produced it;
closing it unmerged is recorded as rejection. Both feed rule health, so
closing a wrong suggestion is useful rather than merely tidy.

ClickUp task: CU-86akeeczr OpenFrame lib batch review findings sweep 2 (13 PRs)

[flamingo]

🦩 What this fix changed, finding by finding

1 finding(s) fixed in this draft — 1 explained inline on the diff.

[flamingo]

🦩 🟠 TagAssignment.entityType/entityId relationship undocumented despite non-obvious polymorphic semantics

Added Javadoc comments in the TagAssignment class body above the entityId field (documenting its polymorphic relationship to entityType), above the entityType field (documenting its role as discriminator for entityId), and above the taggedBy field (documenting its meaning). No behavioral or structural code changes were made, only comments inserted, preserving existing formatting/style.

🤖 Prompt for AI agents

In openframe-data-mongo-common/src/main/java/com/openframe/data/document/tag/TagAssignment.java around line 22, review and complete this code-review fix: TagAssignment.entityType/entityId relationship undocumented despite non-obvious polymorphic semantics.
What the draft fix changed: Added Javadoc comments in the `TagAssignment` class body above the `entityId` field (documenting its polymorphic relationship to `entityType`), above the `entityType` field (documenting its role as discriminator for `entityId`), and above the `taggedBy` field (documenting its meaning). No behavioral or structural code changes were made, only comments inserted, preserving existing formatting/style.
Verify the change is correct and complete; do not refactor unrelated code.

fix confidence: 🟡 70 medium — react 👍/👎 to teach the reviewer

[michaelassraf]

Task linked: CU-86akeeczr OpenFrame lib batch review findings sweep 2 (12 PRs)