RFR: 8336695: Update Commons BCEL to Version 6.10.0

[Johannes Döbler]

On Tue, 23 Sep 2025 21:11:07 GMT, Joe Wang <joehw at openjdk.org> wrote:

> Update Commons BCEL to Version 6.10.0.
> 
> Test: T1-3 passed

I did a quick investigation on XSLTC tests (quick = don't take my word for it). 
In the JDK I did not find many XSLTC tests and none does unit-test internals (XSLTC it is still an almost identical shade of the Apache sources). Tests in Apache Xalan (https://github.com/apache/xalan-test) mostly consist of transformation runs to compare actual with expected results, and I did not find any unit tests for XSLTC compiler classes.
One way forward (see Alan's last comment) could be to test the migration by creating Translet classes for various stylesheets using BCEL and the Classfile API and ideally have byte-identical generated class files.
But imho this whole project requires a deeper discussion:
- Where to get a list of representative stylesheets for such a test?
- Should that test be kept in the JDK test suite for future changes to JDK XSLTC?
- As for now 126 XSLTC classes have BCEL imports. A migration to the Classfile API would create a massive PR.
Should a migration rather be broken down into a series of PRs to allow for efficient reviews?
- Given the current efforts to maintain BCEL in the JDK, the effort to move XSLTC to use the Classfile API and the risk of creating  regressions, an unclear future maintenance effort, would it also be an option to drop XSLTC (and BCEL) from the JDK?

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PR Comment: https://git.openjdk.org/jdk/pull/27459#issuecomment-3347690004