code: public static void cleanup(MountOwner owner) {
          final Set<RegistryEntry> references = ownerReferences.remove(owner);
          if (references != null) {
              for (RegistryEntry entry : references) {
                  entry.removeInboundReference(owner);
              }
          }
          owner.onCleanup();
      }
docs: Cleanup all references from the {@link MountOwner}.  Cleanup any mounted entries that become un-referenced in the process.
  
  @param owner {@link MountOwner} to cleanup references for