code: protected T _parseXml(XCalElement element, ICalParameters parameters, ParseContext context) {
  		XCalValue firstValue = element.firstValue();
  		ICalDataType dataType = firstValue.getDataType();
  		String value = VObjectPropertyValues.escape(firstValue.getValue());
  		return _parseText(value, dataType, parameters, context);
  	}
docs: <p>
  Unmarshals a property from an XML document (xCal).
  </p>
  <p>
  This method should be overridden by child classes that wish to support
  xCal. The default implementation of this method will find the first child
  element with the xCal namespace. The element's name will be used as the
  property's data type and its text content will be passed into the
  {@link #_parseText} method. If no such child element is found, then the
  parent element's text content will be passed into {@link #_parseText} and
  the data type will be null.
  </p>
  @param element the property's XML element
  @param parameters the parsed parameters. These parameters will be
  assigned to the property object once this method returns. Therefore, do
  not assign any parameters to the property object itself whilst inside of
  this method, or else they will be overwritten.
  @param context the context
  @return the unmarshalled property object
  @throws CannotParseException if the scribe could not parse the property's
  value
  @throws SkipMeException if the property should not be added to the final
  {@link ICalendar} object