code: public XcapResponse deleteIfNoneMatch(URI uri, String eTag,
  			Header[] additionalRequestHeaders, Credentials credentials)
  			throws IOException {
  		checkState();
  		return ra.getClient().deleteIfNoneMatch(uri, eTag,
  				additionalRequestHeaders, credentials);
  	}
docs: /*
  (non-Javadoc)
  
  @see XcapClient#deleteIfNoneMatch(java.net.URI,
  java.lang.String, Header[],
  Credentials)