code: @Deprecated
      public static boolean onCharacterBoundary(CharSequence s, int i) {
          return i <= 0 
          || i >= s.length() 
          || !Character.isHighSurrogate(s.charAt(i-1))
          || !Character.isLowSurrogate(s.charAt(i));
      }
docs: Are we on a character boundary?
  
  @deprecated This API is ICU internal only.
  @hide draft / provisional / internal are hidden on Android