fix: preserve head map keys when value is empty

[knyk-dev]

• I have registered the PR changes.

What this PR does:

Which issue(s) this PR fixes:

Fixes #1069

Special notes for your reviewer:

The bug is in the valueLength == 0 branch of decodeHeapMap(). It clears key instead of keeping the decoded key and setting value to an empty string.

And the change is intentionally small and only touches the Getty read/write path plus a regression test.

Does this PR introduce a user-facing change?:
NONE

fix: preserve HeadMap keys when decoding empty header values in Getty RPC messages

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.96%. Comparing base (1b526c3) to head (fde1f46).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1070      +/-   ##
==========================================
+ Coverage   56.91%   56.96%   +0.05%     
==========================================
  Files         266      266              
  Lines       17488    17487       -1     
==========================================
+ Hits         9953     9962       +9     
+ Misses       6706     6704       -2     
+ Partials      829      821       -8     

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[Copilot]

Pull request overview

Fixes a Getty RPC header decoding bug where decodeHeapMap() overwrote the decoded header key when the header value was an empty string, breaking RpcMessage.HeadMap round-tripping.

Changes:

• Fix decodeHeapMap() to preserve the decoded key when valueLength == 0 and set value to "".
• Remove a stray no-op fmt.Sprintln("done") line in the decode loop.
• Add a regression test covering HeadMap entries with empty-string values.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pkg/remoting/getty/readwriter.go	Corrects empty-value decoding behavior so HeadMap keys are not lost/overwritten.
pkg/remoting/getty/readwriter_test.go	Adds a regression test verifying encode/decode round-trip preserves empty header values.

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[thunguo]

LGTM