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, 5e1adf9, 7b02592, 8fcff5e, c38aa78)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.32%. Comparing base (a88681a) to head (c38aa78).
⚠️ Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #8219   +/-   ##
=========================================
  Coverage     90.31%   90.32%           
  Complexity     7653     7653           
=========================================
  Files           843      843           
  Lines         23066    23080   +14     
  Branches       2310     2312    +2     
=========================================
+ Hits          20832    20846   +14     
  Misses         1516     1516           
  Partials        718      718           

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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!

[jack-berg]

Just a nit about preferring parameterized test. Thanks for adding!

[jack-berg]

When testing repeated inputs / outputs, I prefer @ParameterizedTest style, e.g.: https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk/common/src/test/java/io/opentelemetry/sdk/common/internal/GlobUtilTest.java#L17-L57

More readable and less verbose, especially when adding more test cases

[jack-berg]

I think we can probably remove this TODO

[Copilot]

Pull request overview

Adds additional coverage for Value.asString() when the underlying Value is created from UTF-8 bytes, targeting boundary/edge cases.

Changes:

• Replaces the previous single-case valueByteAsString test with a parameterized test including an empty string and other string variants.
• Adds a JQF/GuidedFuzzing-based fuzz test driver to validate byte<->base64<->byte round-tripping for random strings.

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