[ISSUE #10860] Make DefaultPromise.get wait for completion

[yuluo-yx]

Which Issue(s) This PR Fixes

• Fixes [Bug] OpenMessaging DefaultPromise.get returns before completion #10860

Brief Description

The no-argument OpenMessaging DefaultPromise.get() now uses the existing wait path instead of returning a pending null result. The indefinite wait uses a state loop to handle spurious wakeups and restores the interrupt flag when interrupted.

Reading a completed value no longer notifies listeners again. Regression tests cover waiting for completion, failure propagation, and single listener notification.

How Did You Test This Change?

• mise exec java@temurin-17.0.19+10 -- mvn -pl openmessaging -am -Dtest=DefaultPromiseTest -Dsurefire.failIfNoSpecifiedTests=false -Dspotbugs.skip=true test
• Result: BUILD SUCCESS; 12 tests, 0 failures, 0 errors, 0 skipped.
• Scope check: 2 files, 69 changed lines.

[RockteMQ-AI]

Summary

Fixes a critical correctness issue where DefaultPromise.get() returned immediately without waiting for the promise to complete. Also fixes spurious wakeup handling and interrupt flag restoration.

Analysis

• Correctness ✅ — The old get() returning result directly (which is null before completion) defeats the entire purpose of a Promise. The fix to delegate to get(0) with proper wait semantics is correct. The while (isDoing()) loop handles spurious wakeups. The catch (InterruptedException) with Thread.currentThread().interrupt() properly restores the interrupt flag.
• Tests ✅ — Three regression tests covering: basic wait-for-completion, timeout behavior, and the interrupted-flag restoration.
• Compatibility ⚠️ — This is a behavioral change: callers of get() that relied on the old non-blocking behavior will now block. However, the old behavior was clearly a bug (a Promise that doesn't wait is useless), so this is the correct fix.

LGTM.

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Automated review by github-manager-bot

[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.29%. Comparing base (fd0c959) to head (4c97db8).

Files with missing lines	Patch %	Lines
...openmessaging/rocketmq/promise/DefaultPromise.java	50.00%	4 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10865      +/-   ##
=============================================
- Coverage      48.39%   48.29%   -0.10%     
+ Complexity     13562    13535      -27     
=============================================
  Files           1380     1380              
  Lines         101165   101167       +2     
  Branches       13127    13128       +1     
=============================================
- Hits           48962    48862     -100     
- Misses         46233    46318      +85     
- Partials        5970     5987      +17     

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