*
   * <p><b>Note:</b> When implementing an escaper it is a good idea to override this method for
   * efficiency by inlining the implementation of {@link #nextEscapeIndex(CharSequence, int, int)}
   * directly. Doing this for {@link com.google.common.net.PercentEscaper} more than doubled the
   * performance for unescaped strings (as measured by {@code CharEscapersBenchmark}).
   *

          }

          // Inefficient implementation that defines all letters as escapable.
          @Override
          protected int nextEscapeIndex(CharSequence csq, int index, int end) {
            while (index < end && !Character.isLetter(csq.charAt(index))) {
              index++;
            }
            return index;
          }
        };