WebMapLayer.getCopyright() doesn't work

[JasonNewmoyer]

I have loaded a MapView using a publicly published webmap. After the map loads, I attempt to retrieve layer attribution as required by Esri guidelines using WebMapLayer.getCopyright(). But it always returns null. 

String text = "Data Copyrights: <br/>";
for(WebMapLayer layer : webMap.getBaseMap().getBaseMapLayers()) {
    text += "(Basemap) " + layer.getTitle() + ": " + layer.getCopyright() + "<br/>";
}  
for (WebMapLayer layer : webMap.getOperationalLayers()) {
    text += layer.getTitle() + ": " + layer.getCopyright() + "<br/>";
}