[fix][test] Made ProtobufNativeSchemaTest.testSchema order-independent

[LucasEby]

Fixes #24804

Motivation

In ProtobufNativeSchemaTest.testSchema, the json's contents and the FileDescriptorSet field's contents do not have a deterministic order but the hardcoded string assertion assumes a deterministic order. The json serializer did not guarantee attribute order and inside FileDescriptorSet the contents can also be in different orders due to different generation paths or environments producing the contents in different orders despite the logical content being the same. Since the original test compared the raw strings/trees "as-is", harmless re-ordering could flip the test from pass to fail without any real schema change.

Modifications

We no longer compare raw strings/trees "as-is". Instead the fileDescriptorSet field is base64-decoded into a FileDescriptorSet, then converted into a JSONObject. We compare the expected and actual descriptors with JsonAssert in NON_EXTENSIBLE mode, which ignores field ordering but forbids missing or extra fields.

Next, we remove FileDescriptorSet from the outer JSON and compare the remainder in the NON_EXTENSIBLE mode again. We implemented this two stage approach because JSON assertion does not re-order the inner contents of the FileDescriptorSet (compares directly as strings instead) even if though it's decoded contents can be re-ordered.

By decoding and normalizing fileDescriptorSet first, we ensure the test remains robust to nondeterministic ordering inside the descriptor set, while still validating the schema structure strictly. This change keeps the spirit of the original test while eliminating failures caused solely by allowed reordering.

NOTE: Some additional assertTrue and assertFalse assertions were also added to ensure the test remains robust in the event that the hardcoded string is ever modified for some reason. This will prevent someone from modifying the string and then forgetting to modify the test afterwards, thus causing the fileDescriptorSet assertion to incorrectly pass from comparing empty strings.

Verifying this change

• Make sure that the change passes the CI checks.

This change is already covered by existing tests, such as org.apache.pulsar.client.impl.schema.ProtobufSchemaTest#testSchema.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: LucasEby#1

[LucasEby]

@lhotari I incorporated your suggestions and made the code easier to follow. All checks passed on my fork: LucasEby#1
The code should be good to merge

[lhotari]

LGTM

[lhotari]

Closing and reopening to trigger the CI to run with latest master branch since updating PR branch wasn't allowed (please create PRs in a way where it's allowed, this is the default).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.33%. Comparing base (cc0eef9) to head (6f31a65).
⚠️ Report is 93 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #24805      +/-   ##
============================================
- Coverage     74.34%   74.33%   -0.01%     
+ Complexity    33842    33667     -175     
============================================
  Files          1912     1920       +8     
  Lines        149072   150153    +1081     
  Branches      17299    17418     +119     
============================================
+ Hits         110833   111622     +789     
- Misses        29440    29646     +206     
- Partials       8799     8885      +86     

Flag	Coverage Δ
inttests	26.18% <ø> (-0.06%)	⬇️
systests	22.82% <ø> (-0.01%)	⬇️
unittests	73.88% <ø> (+<0.01%)	⬆️

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