code: public static void registerInterest(String sourceKey, String regex, String rewritePattern, TypeReferenceLocation... locations)
      {
          patternsBySource.put(sourceKey, new PatternAndLocation(locations, regex, rewritePattern));
      }
docs: Register a regex pattern to filter interest in certain Java types.
  @param  sourceKey Identifier of who gave the pattern to us (so that we can update it).
  This can be any arbitrary string.