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