RFR: 8202617: javadoc generates broken links to undocumented (e.g. private) members [v2]

[Nizar Benalla]

> Please review this patch to prevent links to private and package-private members to be generated.
> The bug happens when you link to private/package-private members, and javadoc used to generated links to them (assuming they were inherited because the holder is unreachable).
> 
> Taking the code path I changed is very rare, as it only used by 4 anchors in 4 classes in all the JDK.
> 
> if (refSignature.trim().startsWith("#") &&
>                     ! (utils.isPublic(containing) || utils.isLinkable(containing))
> 
> 
> The classes that used it are `StringBuilder`/`StringBuffer` with `#append(java.lang.String)` and `ZipEntry`/`ZipOutputStream` with `#CENHDR`
> 
> 
> I've expanded the test to check whether the links are created when they should be.
> 
> The generated documentation before and after the change are identical.

Nizar Benalla has updated the pull request incrementally with one additional commit since the last revision:

  whitespace

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21802/files
  - new: https://git.openjdk.org/jdk/pull/21802/files/5f8cf1ab..432ba686

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21802&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21802&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21802.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21802/head:pull/21802

PR: https://git.openjdk.org/jdk/pull/21802