RFR: 8367585: Move Utf8Entry length validation earlier

[Chen Liang]

John Rose suggests in https://github.com/openjdk/jdk/pull/26802#issuecomment-3201402304 that ClassFile API should validate Utf8Entry length eagerly upon construction. Currently we validate upon writing to bytes, which avoids validation overhead. However, given that most class file utf8 data are shorter than 1/3 of the max length, which is always an encodable length, the performance impact should be low.

Preventing the creation of unrepresentable UTF8 entries can prevent passing such invalid instances around, making such problems easier to debug than a failure at building.

Tier 1-3 seems clear. The performance impact to jdk.classfile.Write or any of the regularly run transformation benchmarks seems neutral, less than 5% perturbations.

I will update docs to reflect this change, given how widespread this is across JDK - it seems the only exempt classes are Signature, ClassSignature, and MethodSignature.

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Commit messages:
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/cf-utf8-length-early
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/cf-utf8-length-early
 - Stage
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/cf-utf8-length-early
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/cf-utf8-length-early
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/cf-utf8-length-early
 - Avoid being too specific
 - Tests
 - Doc changes
 - 8367585: Move Utf8Entry length validation earlier

Changes: https://git.openjdk.org/jdk/pull/27281/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27281&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367585
  Stats: 416 lines in 15 files changed: 253 ins; 51 del; 112 mod
  Patch: https://git.openjdk.org/jdk/pull/27281.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27281/head:pull/27281

PR: https://git.openjdk.org/jdk/pull/27281