code: private static RuntimeDelegate findDelegate() {
  		RuntimeDelegate result=null;
  		try {
  			result=createRuntimeDelegateFromSPI();
  			if(result==null) {
  				result=createRuntimeDelegateFromConfigurationFile();
  			}
  			if(result==null) {
  				String delegateClassName = System.getProperty(APPLICATION_ENGINE_SPI_PROPERTY);
  				if(delegateClassName!=null) {
  					result=createRuntimeDelegateForClassName(delegateClassName);
  				}
  			}
  		} catch (Exception ex) {
  			LOGGER.warn("Could not find application engine",ex);
  		}
  		return result;
  	}
docs: Obtain an {@code RuntimeDelegate} instance using the method described
  in {@link RuntimeDelegate#getInstance()}.
  
  @return an instance of {@code RuntimeDelegate} if available, or null if
  a default implementation class is to be selected.