test: add empty string and unicode edge cases to ValueTest

[Tusharika725]

Description

Resolves an inline TODO in ValueTest.java to add more test cases.

Added edge cases for the valueByteAsString() method to ensure string encoding/decoding handles boundaries without data loss. Specifically added:

• An empty string boundary.
• A special character/Unicode boundary (testing whitespace, newlines, and a 4-byte emoji).

All local tests pass.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Tusharika725 / name: Tusharika Srivastava (568f3e7, 7b02592, 8fcff5e)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.31%. Comparing base (a88681a) to head (8fcff5e).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8219      +/-   ##
============================================
- Coverage     90.31%   90.31%   -0.01%     
+ Complexity     7653     7652       -1     
============================================
  Files           843      843              
  Lines         23066    23071       +5     
  Branches       2310     2311       +1     
============================================
+ Hits          20832    20836       +4     
  Misses         1516     1516              
- Partials        718      719       +1     

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[jkwatson]

It would be extra-cool if you made this into a fuzz-test that would test a wider variety of possible inputs. I think there are examples of this in the codebase somewhere. (search for "fuzz")

[Tusharika725]

"@jkwatson Thanks for the great suggestion! I've implemented a property-based fuzz test using JQF alongside the original deterministic tests. Let me know if you need any further adjustments!