RFR: JDK-8268420: new Reporter method to report a diagnostic within a DocTree node

[Pavel Rappo]

On Mon, 14 Jun 2021 21:45:11 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

> Please review an update to add a new method in Reporter to report a diagnostic within a DocTree node for those DocTree nodes that wrap a string.
> 
> This is the last of the current round of updates to improve the diagnostics that can be generated by javadoc.
> 
> The general fix, in JavadocLog and Reporter, is pretty simple, given all the improvements in recent related changes.
> 
> There are some cosmetic cleanups that were made while exploring the current solution.
> 
> The test is "reasonably thorough" and uses a custom taglet to generate diagnostics for selected nodes in doc comment trees. The test then "algorithmically validates" (i.e. no golden files or text blocks) the diagnostics that are either passed to a DiagnosticListener or written to the console stream.

Please synchronize the code snippet from the CSR with that of this PR: the method in this PR is neither `default` nor has an `@implNote`. Also, update the copyright years.

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Changes requested by prappo (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4489