A warnning of Cropping1D

I add a cropping1d layer in my computation graph:

.addLayer(“crop”, new Cropping1D.Builder(timeSteps-1,0).build(),net.getPreviousLayer())

And I got a warning like this:

[main] WARN org.deeplearning4j.nn.conf.layers.InputTypeUtil - Automatic addition of RNN -> CNN preprocessors: not yet implemented (layer name: “crop”)

Is that means my crop layer is invalid? Or some errors?