code: public void makeDataFieldCompositeType()
      {
          final EncodedDataType edt = (EncodedDataType)containedTypeByNameMap.get("varData");
          if (edt != null)
          {
              edt.variableLength(true);
          }
      }
docs: Make this composite type, if it has a varData member, variable length
  by making the EncodedDataType with the name "varData" be variable length.