@Override
        public boolean apply(CharSequence input) {
          return (input.length() > 0) && (input.charAt(0) == 'a');
        }
      };

  public void testIndexOf_genericPredicate() {
    List<CharSequence> sequences = Lists.newArrayList();
    sequences.add("bob");
    sequences.add(new StringBuilder("charlie"));
    sequences.add(new StringBuffer("henry"));