[jdk16] RFR: JDK-8249633: doclint reports missing javadoc for JavaFX property methods that have a property description

[Jonathan Gibbons]

There are two parts to the fix:

1. Similar to that of JDK-8251200:  predicate methods in `Utils` used to check if an element has certain tags in its doc comment may trigger the missing comment check even when there does not need to be a comment.

2. When synthesizing comments for the property-related methods, the code checks for the existence of explicit comments, in case they exist; that could also trigger the "missing comment" check.

The fix shares some changes with JDK-8251200; whichever does not go first will need a merge commit.

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Commit messages:
 - fix whitespace
 - JDK-8249633: doclint reports missing javadoc for JavaFX property methods that have a property description

Changes: https://git.openjdk.java.net/jdk16/pull/71/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16&pr=71&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8249633
  Stats: 131 lines in 3 files changed: 99 ins; 21 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk16/pull/71.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16 pull/71/head:pull/71

PR: https://git.openjdk.java.net/jdk16/pull/71