code: boolean defineChar2StringMapping(String outputString, char inputChar) 
      {
          CharKey character = new CharKey(inputChar);
          m_charToString.put(character, outputString);
          set(inputChar);  // mark the character has having a mapping to a String
          
          boolean extraMapping = extraEntity(outputString, inputChar);
          return extraMapping;
          	
      }
docs: Call this method to register a char to String mapping, for example
  to map '<' to "&lt;".
  @param outputString The String to map to.
  @param inputChar The char to map from.
  @return true if the mapping is not one of:
  <ul>
  <li> '<' to "&lt;"
  <li> '>' to "&gt;"
  <li> '&' to "&amp;"
  <li> '"' to "&quot;"
  </ul>