docs: @Override
  	public CompletableFuture<Acknowledge> updateTaskExecutionState(
  			final TaskExecutionState taskExecutionState) {
  		checkNotNull(taskExecutionState, "taskExecutionState");
  
  		if (executionGraph.updateState(taskExecutionState)) {
  			return CompletableFuture.completedFuture(Acknowledge.get());
  		} else {
  			return FutureUtils.completedExceptionally(
  				new ExecutionGraphException("The execution attempt " +
  					taskExecutionState.getID() + " was not found."));
  		}
  	}