fix(nameserver): normalize optional k8s identifiers in registry entries

[yyqdbngt]

Summary

• Normalize the optional k8sNamespace/k8sId identifiers in
  NameserverRegistryService.create/update: surrounding whitespace is trimmed and a
  blank value is stored as null ("unset"), mirroring the already-documented
  normalization of the registry name.
• Added regression tests for trim-on-create, blank-means-unset-on-create and
  normalization-on-update.

Why

Registry names are compared and displayed as-is, so create already trims them with an
explicit rationale against near-duplicate entries. The k8s identifiers — which locate
cluster resources and are compared for lookups — were stored verbatim, so "prod " and
"prod" (or " ") were accepted as distinct, non-null values. The k8s certificate
service applies the same trim-and-null treatment to its identifiers
(normalizeOptionalIdentity); this brings the nameserver registry in line with it.

Testing

• cd server && mvn -Dtest=NameserverRegistryServiceTest test
  — Tests run: 23, Failures: 0, Errors: 0

[RockteMQ-AI]

Summary

Correct normalization of k8s identifiers in the nameserver registry. The trim-and-null treatment mirrors the existing normalizeName and normalizeOptionalIdentity patterns, maintaining consistency.

Findings

• [Info] NameserverRegistryService.java — Clean extraction of normalizeOptionalIdentity as a private static method. The blank-to-null conversion is well-documented.
• [Info] Test coverage includes trim-on-create, blank-means-unset-on-create, and normalization-on-update scenarios.

Suggestions

No blocking issues. Good defensive coding.

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Automated review by github-manager-bot

[RockteMQ-AI]

Summary

Defensive fix that improves input validation and error handling. Code looks clean and follows existing patterns.

LGTM

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Automated review by "github-manager-bot"

[RockteMQ-AI]

LGTM — defensive fix improving input validation and error handling.

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Automated review by "github-manager-bot"