code: public void typeSystemInit(TypeSystem aTypeSystem) throws AnalysisEngineProcessException {
     // initialize types for the regex concepts
     if (this.regexConcepts != null) {
       try {
         for (int i = 0; i < this.regexConcepts.length; i++) {
           ((Concept_impl) this.regexConcepts[i]).typeInit(aTypeSystem);
         }
       } catch (ResourceInitializationException ex) {
         throw new RegexAnnotatorProcessException(ex);
       }
     }
   }
docs: Acquires references to CAS Type and Feature objects that are later used during the
  {@link #process(CAS)} method.