RFR: 8272515: JFR: Names should only be valid Java identifiers

[Erik Gahlin]

Hi,

Could I have a review of change that prevents invalid Java identifiers or type names in JFR events. For rationale and compatibility issues see the CSR request. The only change to java.base is making jdk.modules.internal.Checks::isJavaIdentifier(String) public, so it can be reused by the jdk.jfr module.

Testing: /jdk/jdk/jfr + tier1 + tier2

Thanks
Erik

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Commit messages:
 - Improve guard against invalid type
 - Remove unused imports
 - Initial

Changes: https://git.openjdk.java.net/jdk/pull/5415/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5415&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272515
  Stats: 308 lines in 11 files changed: 259 ins; 23 del; 26 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5415.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5415/head:pull/5415

PR: https://git.openjdk.java.net/jdk/pull/5415