The GeoJSON layer definition (per-layer clustering override, and the
declared geometry, which answers for a layer that ships empty).
The layer's GeoJSON data (probed for Point features). Empty, the layer is clustered only if it declares a point geometry.
Decides the clustering strategy for a single GeoJSON layer, returning
{ shouldCluster }. Reads the capability config (modules.cluster); returns_CLUSTER_NONEwhen the capability is disabled.