code: @Override
      public boolean isReturnTypeReferenceType() {
          SignatureParser parser = new SignatureParser(getSignature());
          String returnTypeSig = parser.getReturnTypeSignature();
          return SignatureParser.isReferenceType(returnTypeSig);
      }
docs: /*
  (non-Javadoc)
  
  @see edu.umd.cs.findbugs.ba.XMethod#isReturnTypeReferenceType()