code: @Override
      protected String escapeCharacter(char ch, char previousChar) {
        if(ch < ' ' && ch != '\t' && ch != '\n' && ch != '\r') {
            return "";
        }
        switch(ch) {
            case '&': return ESCAPED_AMP;
            case '<': return ESCAPED_LT;
            case '>': return ESCAPED_GT;
            case '"': return ESCAPED_QUOTE;
            case '\'': return  ESCAPED_APOS;
            case '\\': return  ESCAPED_BACKSLASH;
            case '@': return ESCAPED_AT;
            case '`': return ESCAPED_BACKTICK;
            case NBSP: return ESCAPED_NON_BREAKING_SPACE;
            case LINE_SEPARATOR: return ESCAPED_LINE_SEPARATOR;
            case PARAGRAPH_SEPARATOR: return ESCAPED_PARAGRAPH_SEPARATOR;
        }
        return null;
      }
docs: /* (non-Javadoc)
  @see AbstractCharReplacementEncoder#escapeCharacter(char, char)