RFR: JDK-8310571: Use inline @return tag on java.util.Objects [v3]

[Joe Darcy]

> Small cleanup, minor differences in the wording of portions of toString(Object, String), nonNull(Object), requireNonNullElse, and requireNonNullElseGet.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Make sure there is not an unwanted word break around "non-null".

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14608/files
  - new: https://git.openjdk.org/jdk/pull/14608/files/d97eb7ab..7fae1b74

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14608&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14608&range=01-02

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/14608.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14608/head:pull/14608

PR: https://git.openjdk.org/jdk/pull/14608