PMD's "Avoid Duplicate Literals" has a boolean configuration option,
skipAnnotations, to prevent literals like "unchecked" in the annotation
@SuppressWarnings("unchecked") to be counted as duplicates.
The default value is false. I set it to true, but alas, literals in
annotations are still counted as violations. Should I have configured it
differently (like 1, or True, or yes), or is there something else going on?