code: public WordBuilder<I> reverse() {
          ensureUnlocked();
          int lowIdx = 0, highIdx = length - 1;
  
          while (lowIdx < highIdx) {
              Object tmp = array[lowIdx];
              array[lowIdx++] = array[highIdx];
              array[highIdx--] = tmp;
          }
  
          return this;
      }
docs: Reverses the contents of the internal buffer.
  
  @return {@code this}