code: int addType(final String type) {
          key.set(TYPE_NORMAL, type, null, null);
          Item result = get(key);
          if (result == null) {
              result = addType(key);
          }
          return result.index;
      }
docs: Adds the given internal name to {@link #typeTable} and returns its index.
  Does nothing if the type table already contains this internal name.
  
  @param type
  the internal name to be added to the type table.
  @return the index of this internal name in the type table.