I hope I am not too late to the party here.
But as of Design Support Library 28.0.0-alpha1
you can use the property
app:labelVisibilityMode="unlabeled"
you can use other values "auto", "labeled" and "selected" as well.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
