code: private Item newString(final String value) {
          key2.set(STR, value, null, null);
          Item result = get(key2);
          if (result == null) {
              pool.put12(STR, newUTF8(value));
              result = new Item(index++, key2);
              put(result);
          }
          return result;
      }
docs: Adds a string to the constant pool of the class being build. Does nothing
  if the constant pool already contains a similar item.
  
  @param value
  the String value.
  @return a new or already existing string item.