code: public String write(Integer indent, String xmlVersion) {
  		return write(new XCalOutputProperties(indent, xmlVersion));
  	}
docs: Writes the xCal document to a string.
  @param indent the number of indent spaces to use for pretty-printing or
  "null" to disable pretty-printing (disabled by default)
  @param xmlVersion the XML version to use (defaults to "1.0") (Note: Many
  JDKs only support 1.0 natively. For XML 1.1 support, add a JAXP library
  like <a href=
  "http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22xalan%22%20AND%20a%3A%22xalan%22"
  >xalan</a> to your project)
  @return the XML string