code: public static boolean contains(CharSequence self, CharSequence text) {
          int idx = self.toString().indexOf(text.toString());
          return idx >= 0;
      }
docs: Provide an implementation of contains() like
  {@link java.util.Collection#contains(Object)} to make CharSequences more polymorphic.
  
  @param self a CharSequence
  @param text the CharSequence to look for
  @return true if this CharSequence contains the given text
  @see #contains(String, String)
  @since 1.8.2