[Rev 01] RFR: 6724: Agent argument as a path to a probe definition XML should be optional

[Kangcheng Xu]

> This patch addresses [JMC-6724: Agent argument as a path to a probe definition XML should be
> optional](https://bugs.openjdk.java.net/browse/JMC-6724). It makes the agent argument optional and probes can always be
> defined later via JMX. If such an argument is missing, an empty registry is created with no transform descriptor.

Kangcheng Xu has updated the pull request incrementally with one additional commit since the last revision:

  Update documentation

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/63/files
  - new: https://git.openjdk.java.net/jmc/pull/63/files/b0148997..b7e05c34

Webrevs:
 - full: https://webrevs.openjdk.java.net/jmc/63/webrev.01
 - incr: https://webrevs.openjdk.java.net/jmc/63/webrev.00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jmc/pull/63.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/63/head:pull/63

PR: https://git.openjdk.java.net/jmc/pull/63