Assigning features to spatial clusters created by Oracle SDO_SAM.SPATIAL_CLUSTERS

SDO_SAM.SPATIAL_CLUSTERS creates spatial clusters – how to detect which feature was assigned to which cluster? Is the only way to perform an additional spatial join between cluster geometries and original features?

For comparison: Spatial clustering functions in PostGIS like ST_ClusterKMeans return a cluster ID for each feature, not the cluster geometry.