[ISSUE #10890] Validate gRPC client language metadata

[Aias00]

What is the purpose of the change

Malformed or missing gRPC language metadata reached LanguageCode.valueOf and was reported as a server-side INTERNAL error.

Closes #10890

Brief changelog

• centralize gRPC client language parsing in ClientActivity;
• reject blank and unknown values with Code.BAD_REQUEST;
• use the same validation for telemetry registration and client termination;
• add a telemetry regression test that verifies invalid language maps to gRPC INVALID_ARGUMENT.

Verifying this change

JAVA_HOME=$(/usr/libexec/java_home -v 1.8) PATH="$JAVA_HOME/bin:$PATH" \
  mvn -q -pl proxy -am -Dtest=ClientActivityTest -DfailIfNoTests=false test

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.54%. Comparing base (293f588) to head (2d79a49).

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10891      +/-   ##
=============================================
- Coverage      48.60%   48.54%   -0.07%     
+ Complexity     13690    13668      -22     
=============================================
  Files           1381     1381              
  Lines         101464   101470       +6     
  Branches       13187    13188       +1     
=============================================
- Hits           49318    49259      -59     
- Misses         46158    46199      +41     
- Partials        5988     6012      +24     

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[RockteMQ-AI]

Summary

This PR centralizes gRPC client language parsing in ClientActivity.parseLanguage(), replacing 3 direct LanguageCode.valueOf() calls that would throw unhandled exceptions on malformed input. Previously, these would surface as gRPC INTERNAL errors (server-side fault); now they correctly map to BAD_REQUEST / INVALID_ARGUMENT (client-side fault).

Verdict: LGTM — clean, focused defensive programming fix with good test coverage.

Findings

• [Info] proxy/.../ClientActivity.java:462-470 — The parseLanguage method uses StringUtils.isBlank() for the empty check, which is good. Consider also trimming the input before valueOf() to handle whitespace-only values (e.g., " ") consistently — isBlank catches this, but the error message "unsupported language: " could be slightly confusing. Minor, not blocking.

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Automated review by "github-manager-bot"

[RockteMQ-AI]

Summary

Centralizes gRPC language metadata parsing and rejects invalid values. Prevents INTERNAL errors from malformed input.

LGTM.

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Automated review by github-manager-bot

[Aias00]

Rebased onto current develop and validated ClientActivityTest with the proxy module. The prior macOS compile failure will be retried by the refreshed branch.