propertize doesn't seem to be working for all classes - QGIS 3

Given a reference to a layer, none of this works:

```
layer.p_c ---> TAB!
layer.p_cacheImage            layer.p_children       layer.p_connect       
layer.p_capabilitiesString    layer.p_commitChanges  layer.p_crs           
layer.p_changeAttributeValue  layer.p_commitErrors   layer.p_customProperty

```