code: public char getEndInputKey() {
          String value = Optional.fromNullable(getParameter(SignalParameters.END_INPUT_KEY.symbol())).or("");
          return value.isEmpty() ? '#' : value.charAt(0);
      }
docs: Specifies a key that signals the end of digit collection or voice recording.
  <p>
  <b>The default end input key is the # key.</b> To specify that no End Input Key be used the parameter is set to the
  string "null".
  <p>
  <b>The default behavior not to return the End Input Key in the digits returned to the call agent.</b> This behavior can
  be overridden by the Include End Input Key (eik) parameter.
  </p>
  
  @return