RFR: 8263380: Unintended use of Objects.nonNull in VarHandles

[Claes Redestad]

Use requireNonNull instead.

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Commit messages:
 - Unintended use of Objects.nonNull in VarHandles

Changes: https://git.openjdk.java.net/jdk/pull/2914/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2914&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263380
  Stats: 14 lines in 1 file changed: 0 ins; 0 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2914.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2914/head:pull/2914

PR: https://git.openjdk.java.net/jdk/pull/2914