RFR: 8288783: JFR: Error messages are confusing when options conflict in -XX:StartFlightRecording [v5]

[Chihiro Ito]

> Could I have a review of PR that fixes incorrect error messages regarding of recording.
> 
> The current message is very confusing. If a user types jcmd <pid> JFR.start name=abc name=def or java --XX:StartFlightRecording=name=abc,name=def,  the error message says "Duplicates in diagnostic command arguments", but doesn't know what options are duplicated.
> Furthermore, if a user specifies two or three duplicate parameters, the same logs will be output.
> 
> It should say follows,
> Option name can only be specified once with starting flight recording
> Options name and disk can only be specified once with starting flight recording
> Options name, disk and maxage can only be specified once with starting flight recording
> This problem affects --XX:StartFlightRecording, jcmd JFR.start, JFR.stop, JFR.dump, JFR.check, and MBean.
> 
> For other than start, the output is as follows, (example of dump)
> Option name can only be specified once with dumping flight recording
> 
> Testing: jdk/jdk/jfr
> 
> Thanks
> Chihiro

Chihiro Ito has updated the pull request incrementally with two additional commits since the last revision:

 - Update test/jdk/jdk/jfr/startupargs/TestStartupOptionSpecifiedOnce.java
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
 - Update src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/ArgumentParser.java
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9302/files
  - new: https://git.openjdk.org/jdk/pull/9302/files/3b901828..d1f68a7e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9302&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9302&range=03-04

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9302.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9302/head:pull/9302

PR: https://git.openjdk.org/jdk/pull/9302