[jdk11u-dev] RFR: 8278519: serviceability/jvmti/FieldAccessWatch/FieldAccessWatch.java failed "assert(handle != __null) failed: JNI handle should not be null"

[Goetz Lindenmaier]

I backport this for parity with 11.0.17-oracle.

Clean except for Copyright. Will mark clean.

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Commit messages:
 - Backport 63e43030ed1260d14df950342c39a377231a3f40

Changes: https://git.openjdk.org/jdk11u-dev/pull/1167/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1167&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8278519
  Stats: 14 lines in 2 files changed: 8 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1167.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1167/head:pull/1167

PR: https://git.openjdk.org/jdk11u-dev/pull/1167