[agamal026]

Problem

BEANUTILS-417: DynaProperty.writeObject writes custom class metadata before default fields. The actual JBoss Marshalling serializing ObjectCloner rejects this ordering with IllegalStateException: defaultWriteObject may not be called in this context.

This targets the maintained 1.X branch and follows the earlier maintainer requirement: a new writer format is permitted if the new reader accepts both old and new data. Callers continue to use their ordinary ObjectInputStream.

Change

• Write default fields before the existing custom type/content-type encoding.
• Add an empty, package-private serializable superclass. When it is absent from a historical stream, readObjectNoData() marks the legacy ordering before DynaProperty reads its data. New streams include the marker and use the new ordering.
• Always write the new format, including objects read from historical streams. Preserve DynaProperty's UID 1L, public/protected members, transient class fields and primitive-class codec.
• Add test-scoped JBoss Marshalling 2.0.12.Final coverage, legacy-read/rewrite/clone transitions and subclass-state checks. Keep all 22 historical .ser fixtures and their existing reader test unchanged; update the three assertions that deliberately checked the old writer order.
• Document the compatibility boundary and permanent marker commitment; add a scoped changelog entry.

Compatibility qualification

Japicmp reports DynaProperty as binary- and source-compatible, with UID 1L retained, and explicitly flags SERIALIZABLE_INCOMPATIBLE_SUPERCLASS_MODIFIED. This finding has not been suppressed. The added superclass, including its name, UID, empty persistent form and position, becomes part of the serialized protocol; reflection observes the hierarchy change.

The intended guarantee is new readers accept historical and new data. Earlier library releases reading newly written data are not supported by this change. The legacy fixtures, new round trips and an unchanged baseline-compiled subclass exercise the intended direction.

Executed proof

Source: 1d95c95c3045da8939db4c93ba2d13cf27ae241f, based on 22354f22fb150f82ae8cb7d4e444d2bf0d2bb1ff.

Immutable proof packet — full sanitized logs, exact commands/timestamps, source and fixture hashes, failed/skipped cases, gate reports, a tests-only baseline patch, and the precompiled-client evidence. The proof lives on a separate fork branch; this PR changes five source/test/changelog/build files.

Run	Reported	Passed	Failures	Errors	Skipped
Unchanged production + candidate tests	104	91	3	9	1
Fixed focused suite	104	103	0	0	1
Full configured default build	1,293	1,285	0	0	8

The baseline has three writer-order assertion failures and nine strict-cloner errors. Primitive-int cloning already passes on the baseline; all twelve former failure/error cases pass with the fix. One active compatibility test reads the 22 unchanged fixtures; these are not counted as 22 separate JUnit cases.

The supplemental client/subclass was compiled once against baseline classes, then its unchanged bytecode passed write and read/rewrite modes against the fixed classes. It checks constructor/protected-field linkage, UID, historical subclass input and subclass-specific final state.

Focused command: mvn -Dtest=DynaProperty* clean test. Full validation used Maven without an explicit goal or test selector, executing the unchanged default clean apache-rat:check verify japicmp:cmp javadoc:javadoc checkstyle:check. RAT: 292 approved, zero unknown/unapproved; Checkstyle: zero violations; Japicmp completed with the qualification above; Javadoc generated. Full logs retain the nonfatal dependency-metadata/SPDX and schema warnings, including a minimal SPDX package for the existing test-framework dependency.

Environment: Maven 3.9.11, OpenJDK 17.0.20, Linux amd64, compiler release 8. Environment-only JDK-module launchers replace missing native launchers. The full run reports eight skips in unchanged tests; the existing memory-test exclusions remain unchanged. No Java 8 runtime, other platform, full application-server, coverage-percentage or hosted-CI result is claimed. Tests ran before commit creation; all captured fixed-run source bytes were subsequently verified against the linked commit and complete tree.

Contribution checklist and AI disclosure

• Read the contribution guidelines and ASF Generative Tooling Guidance.
• Ran the required default Maven build and meaningful failing-baseline/passing-fixed checks.
• Kept the patch scoped and provided a meaningful issue-linked commit.
• AI used: OpenAI ChatGPT (GPT-6 Astra Pro) generated the implementation, tests, documentation, PR text and proof, with separate AI design/integration/evidence reviews and actual tool-executed validation. This does not claim human review. The commit includes a Generated-by trailer.