Suggested uses:
- Visually marking public and private packages as such.
- Editor code completion could refuse to include private packages from
other compilation units.
- Javadoc editing tools (the suggestions provider and/or AutoComment) could
treat missing or incomplete Javadoc in private packages as a minor error, or
not an error.
If the Java Project module is enabled, you may register an implementation
to the lookup for a project rather than the default lookup.