code: public Collection<ServletTimer> getTimers() {
  		if(!isValid()) {
  			throw new IllegalStateException("SipApplicationSession already invalidated !");
  		}
  		if(servletTimers != null) {
  			return servletTimers.values();
  		}
  		return new HashMap<String, ServletTimer>().values();
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipApplicationSession#getTimers()