private VectorLayer getVectorLayer(final int zLevel, final boolean createIfNonexisting) {
        return getZLevelLayer(zLevel, vectorLayerMap, VectorLayer.class, createIfNonexisting ? () -> new VectorLayer(map) : null);
    }
mimics {@link #removeItem(MarkerInterface)} but w/o calling 'populate'
main/src/main/java/cgeo/geocaching/unifiedmap/geoitemlayer/MapsforgeVtmGeoItemLayer.java