Fixes #413

Summary

This PR updates Jython for runtime compatibility with JDK 25 while keeping the release built with the lowest supported JDK target. The release artifacts were built with JDK 8 and then tested on JDK 8, 11, 17, 21, and 25 from the same build output. No multi-release JAR was needed.

This builds on the already-merged jffi update from #409 and incorporates/adapts fixes from:

• Property sun.stdout.encoding is undefined in recent Java versions #407 for stdout.encoding / sun.stdout.encoding handling on newer JDKs
• Allow native access in JDK 25 #410 for JDK 25 native-access and module-open handling

Changes

• Add JDK 25 runtime launcher support:
  • --enable-native-access=ALL-UNNAMED
  • --sun-misc-unsafe-memory-access=allow
• Add JDK 9+ launcher/module opens needed by current runtime dependencies:
  • java.base/java.io
  • java.base/sun.nio.ch
• Add matching manifest attributes to runtime/test jars:
  • Enable-Native-Access: ALL-UNNAMED
  • Add-Opens: java.base/java.io java.base/sun.nio.ch
• Update ASM from 9.7 to 9.9.1.
• Add jython.test.java.opts so CI/test runs can pass Java proxy/system properties without editing build files.
• Added new test-built Ant target that runs the tests without calling developer-build
• Adjust version-sensitive tests for behavior changes in newer JDKs.
• Skip SecurityManager and class-unloading leak tests where they are no longer valid on JDK 25.
• Improve proxy-aware network tests while preserving direct localhost behavior.
• Make modjy test failures propagate as process failures.
• Suppress test-only noisy Netty logging from deliberate httplib socket error paths.
• Release any partially consumed Netty socket buffer held in incoming_head during socket close.
• Make test_mailbox.test_clean robust against stale deterministic tmp/foo and tmp/bar files.
• Copy profile.properties into dist/javalib and adjust the bundled JIP profiler properties so the Java 8/11 --profile launcher tests produce output without noisy agent stack traces.
• On Java 13+, report --profile as unsupported because the bundled Java Interactive Profiler agent is not compatible with modern class verification.

Proxy-sensitive network tests

When an external HTTP proxy is configured, this PR skips only the network cases that cannot work through an HTTP proxy:

• test_urllib2net external FTP test is skipped when an external HTTP proxy is configured because it requires direct FTP access. Neither FTP-over-HTTP-proxy support nor Java FTP proxy property support is implemented in this PR.
• test_ssl_jy raw external SSL socket tests are skipped because they open raw sockets and cannot use HTTP CONNECT.
• test_smtpnet raw external SMTP SSL tests are skipped because they require direct SMTP-over-SSL socket access.

Higher-level external HTTPS tests were adjusted to use CONNECT where appropriate. Localhost/direct tests continue to run directly.

The relevant generic configuration surfaces for proxied test environments are:

• Environment variables: http_proxy, https_proxy, no_proxy.
• Java system properties passed through jython.test.java.opts system property:
  • http.proxyHost
  • http.proxyPort
  • http.nonProxyHosts
  • https.proxyHost
  • https.proxyPort
  • https.nonProxyHosts.

Validation

Release artifacts were built with JDK 8 using ant clean full-build:

• dist/jython.jar
• dist/jython-standalone.jar
• dist/jython-installer.jar

The resulting artifacts still target JDK 8 bytecode/release metadata.

The regression matrix was run with:

• JDK 8: ant test
• JDK 11: ant test-built
• JDK 17: ant test-built
• JDK 21: ant test-built
• JDK 25: ant test-built

Results:

• JDK 8: 388 tests OK, 2 tests skipped; modjy OK (104 tests); BUILD SUCCESSFUL.
• JDK 11: 388 tests OK, 2 tests skipped; modjy OK (104 tests); BUILD SUCCESSFUL.
• JDK 17: 388 tests OK, 2 tests skipped; modjy OK (104 tests); BUILD SUCCESSFUL.
• JDK 21: 388 tests OK, 2 tests skipped; modjy OK (104 tests); BUILD SUCCESSFUL.
• JDK 25: 388 tests OK, 2 tests skipped; modjy OK (104 tests); BUILD SUCCESSFUL.

The two top-level skipped tests are existing resource-gated tests:

• test_codecmaps_hk, requires urlfetch
• test_curses, requires curses

They are not JDK 25 failures and are not proxy-related.

Additional focused checks used during development included JDK 25 command-line behavior, float behavior, imports, Java integration, subprocess/threading behavior, HTTP/URL handling, warning suppression, test_mailbox cleanup, and JDK 21/JDK 25 socket/SSL behavior.