RFR: 8260349: Cannot programmatically retrieve Metaspace max set via JAVA_TOOL_OPTIONS [v3]

[David Holmes]

> A simple but long standing bug whereby the MemoryPool MXBean only sees the value of MaxMetaspaceSize if it was set directly on the command-line and not by other means (e.g. env var).
> 
> Fix is to check !FLAG_IS_DEFAULT rather than FLAG_IS_CMDLINE.
> 
> Expanded regression test added (based on the reproducer in the JBS issue) that checks all the ways to set the flag: cmd-line, env-var, hotspotrc file
> 
> Testing: regression test (before and after fix)
>              tiers 1-3 (in progress)
> 
> Thanks,
> David

David Holmes has updated the pull request incrementally with one additional commit since the last revision:

  Added missing test case for flag not set

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2275/files
  - new: https://git.openjdk.java.net/jdk/pull/2275/files/8c814dce..a21b75be

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2275&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2275&range=01-02

  Stats: 9 lines in 1 file changed: 7 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2275.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2275/head:pull/2275

PR: https://git.openjdk.java.net/jdk/pull/2275