Bring over upstream #1707 (Java 25 syntax) and #1786 (JDK 27 end positions)

[abashev]

Closes #22. It also carries the JDK matrix from #29, which was closed without merging, so the tests run on JDK 25, 26 and 27 as well.

From upstream, with the authors kept

• Support JDK 27 end positions (JDK-8372948) palantir/palantir-java-format#1786 by Sylwester Lachiewicz, commit authored by him. JDK 27 (JDK-8372948) removed EndPosTable and JCCompilationUnit.endPositions. Trees now resolves the end-position API through a method handle, and Trees.newParser passes the parser flags in the order each JDK expects. The changelog commit is left out.
• Format module imports, compact source files, and unnamed patterns palantir/palantir-java-format#1707 by Pavel Finkelshtein (asm0dey), 15 commits squashed into one, authored by him and keeping upstream's Co-authored-by trailer.
  • Formats import module …; (JEP 511), compact source files (JEP 512) and unnamed patterns such as case Box(_, _) (JEP 456).
  • ImportOrderer renders each import from its tokens.
  • Paths moved to open-java-format/.
  • Left out: the changelog, gradle/jdks/25/**, the gradle-jdks build changes and their testJdk23/testJdk25 tasks, and the README changes.

Added here

• var on JDK 27. After Support JDK 27 end positions (JDK-8372948) palantir/palantir-java-format#1786, every var declaration still failed on JDK 27: 24 golden tests. JDK 27 (JDK-8268850) gives var a VarTypeTree where older JDKs have no type, and this visitor has no visitVarType, because it compiles against JDK 21. Two changes fix it:
  • declareOne checks the var token first, the same reordering as google/google-java-format@075e025c94;
  • binding patterns treat a VAR_TYPE node as var.
• Native metadata for the Support JDK 27 end positions (JDK-8372948) palantir/palantir-java-format#1786 method handles. The image is built with --exact-reachability-metadata. Built without these entries, it failed on every file, even class A{int x;}, with "Cannot reflectively access method JCTree#getEndPosition(EndPosTable)".
• FormatterVersionTest wired to -PjavaRuntime. A jdk leg that runs on the wrong JDK fails.
• Native smoke test. It now also formats a Java 25 compact source file with import module and Box(_, _).
• Full exceptions in test logs. The short form hid the formatter's message and TestKit build output.
• JDK 27 leg skips the Gradle plugin's tests. The matrix names each leg's extra Gradle arguments and the reason for them, shown as a notice. Only JDK 27 has any: -x :gradle-open-java-format:test. Gradle 9.7.1 does not run on Java 27 yet, so TestKit builds there fail with "Unsupported class file major version 71".

Merged with main

main has since gained #43 and #44, which change the same import code. The merge, ecc0647, keeps both:

• An import carries the comments on the lines before it (Keep comments between imports with the import after them #44) and its declaration rendered from its tokens (Format module imports, compact source files, and unnamed patterns palantir/palantir-java-format#1707). Format module imports, compact source files, and unnamed patterns palantir/palantir-java-format#1707's handling of block comments on the import's own line already covers Keep comments between imports with the import after them #44's.
• Javadoc right after an import's ; is no longer an error. Format module imports, compact source files, and unnamed patterns palantir/palantir-java-format#1707 rejected it because the formatter moves it onto a line of its own, which used to separate the imports. Since Keep comments between imports with the import after them #44, a comment between imports goes with the import after it, and so does this one.
• Two copies of an import that differ only in the comment on the lines before them no longer collapse into one, so the comment is kept. Format module imports, compact source files, and unnamed patterns palantir/palantir-java-format#1707 already kept copies that differ in a comment inside the declaration.
• RemoveUnusedImports walks module imports as Format module imports, compact source files, and unnamed patterns palantir/palantir-java-format#1707 does, and cleans up blank lines around deleted imports as Stop an unused import from leaving two blank lines behind #43 does.

Checked

• CI: all 9 jobs are green on the merge commit ecc0647. The JDK 27 leg ran 1502 tests and all of them passed, FormatterVersionTest included, which confirms that the run used JDK 27. The native smoke test passed on all five platforms.

• Tests: after the merge, all 1493 formatter tests pass on JDK 21.

• Same output as main. Both the main jar (43f5d3d) and the merged branch's jar were run over two corpora:

  Corpus	Files	Changed by the formatter	Differ between main and this branch
  JDK 21 sources, on Temurin 21	15,747	14,090	0
  JDK 25 sources, on Corretto 25	15,368	13,635	0

  Neither jar reports an error. The "Imports not contiguous" failures from the earlier check are gone, because Keep comments between imports with the import after them #44 handles comments between imports.

• The merge's edge cases, end to end. Each case formats, and a second run leaves the output unchanged:

  • a javadoc after an import;
  • a javadoc after the last import;
  • comments inside, before and after declarations, next to a static import;
  • a duplicate with a comment before it;
  • unused imports around a comment.