Describe the PR

This PR consistently adds the new custom javadoc tag "internalApi", where it is missing.
Essentially, it proposes the following template:

/**
 * @internalApi None of this is published API, and compatibility can be broken anytime! Use this only at your own risk.
 */
@InternalApi
public ...

The InternalApi annotation is only needed for public/protected members. For package-private members or types in "internal" packages, it's not needed (and we don't generally use it there).

Note, we could extend the template to contain a warning, like we do for the InternalApiBridge classes:

/**
 * Internal API.
 *
 * <p>Acts as a bridge between outer parts of PMD and the restricted access
 * internal API of this package.
 *
 * <p><b>None of this is published API, and compatibility can be broken anytime!</b>
 * Use this only at your own risk.
 *
 * @internalApi None of this is published API, and compatibility can be broken anytime! Use this only at your own risk.
 */

Related issues

• Fix #

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)