code: public static String[] parameter2Array(final IRequestParameters _parameters,
                                             final String _parameterName)
      {
          final List<StringValue> values = _parameters.getParameterValues(_parameterName);
          return ParameterUtil.stringValues2Array(values);
      }
docs: Get an array for the StringValues.
  
  @param _parameters IRequestParameters
  @param _parameterName name of the Paramaters
  @return always StringArray, if parameter does not exist an empty
  StringArray