code: @VisibleForTesting
  	List<Container> getContainersFromPreviousAttemptsUnsafe(final Object response) {
  		if (method != null && response != null) {
  			try {
  				@SuppressWarnings("unchecked")
  				final List<Container> containers = (List<Container>) method.invoke(response);
  				if (containers != null && !containers.isEmpty()) {
  					return containers;
  				}
  			} catch (Exception t) {
  				logger.error("Error invoking 'getContainersFromPreviousAttempts()'", t);
  			}
  		}
  
  		return Collections.emptyList();
  	}
docs: Same as {@link #getContainersFromPreviousAttempts(RegisterApplicationMasterResponse)} but
  allows to pass objects that are not of type {@link RegisterApplicationMasterResponse}.