How to deal with padding (0 vector) without maskZero in ConvolutionLayer?

I find there is no maskZero for the temporalConvolutionLayer.
In this case, if we meet a window of all embeddings are paddings, which means 0 vectors., 
I think the convolution layer will always give us the bias.

But wouldn't the output be 0? Or we don't need maskZero in Convolution Layer?