You can retrieve the visibility layers from a view by comparing the type names of the models with the constants defined in the TLcyShapeVisibilityAddOn. For example, the following snippet can be used to find the layer containing the observers: 

ILspLayer observerLayer = view.getLayers()
                              .stream()
                              .filter(layer -> Objects.equals(TLcyShapeVisibilityAddOn.OBSERVER_MODEL_TYPE_NAME,
                                                              layer.getModel().getModelDescriptor().getTypeName()))
                              .findFirst()
                              .orElse(null);