RFR: 8226216: parameter modifiers are not visible to javac plugins across compilation boundaries [v4]

[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.

Guoxiong Li has updated the pull request incrementally with one additional commit since the last revision:

  Revise test code.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1890/files
  - new: https://git.openjdk.java.net/jdk/pull/1890/files/6fb16609..560f0abb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1890&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1890&range=02-03

  Stats: 8 lines in 1 file changed: 1 ins; 3 del; 4 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