code: public void setMethodParam(String method) {
  		if(isModifiable == ModifiableRule.NotModifiable) {
  			throw new IllegalArgumentException("method param of the URI is not modifiable and must not be set by the application");
  		}
  		try {
  			getSipURI().setMethodParam(method);
  			super.parameters.put(METHOD, method);
  		} catch (ParseException e) {
  			logger.error("parse exception occured", e);
  			throw new IllegalArgumentException("Bad arg " + method, e);
  		}
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipURI#setMethodParam(java.lang.String)