RFR: 8226216: parameter modifiers are not visible to javac plugins across compilation boundaries

[Guoxiong Li]

Hi all,

javac fails to read modifiers from the MethodParameters attribute in class files, which prevents plugins from accessing those modifiers across compilation boundaries. Because `com.sun.tools.javac.jvm.ClassReader` doesn't read and store the access flags(modifiers) from MethodParameters attribute.

This patch fixes it and adds a corresponding test case. All the existing tests of javac passed locally.

Thank you for taking the time to review.

Best Regards.

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Commit messages:
 - 8226216: parameter modifiers are not visible to javac plugins across compilation boundaries

Changes: https://git.openjdk.java.net/jdk/pull/1890/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1890&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8226216
  Stats: 172 lines in 2 files changed: 171 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1890.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1890/head:pull/1890

PR: https://git.openjdk.java.net/jdk/pull/1890