@Override
        public Object call() {
          PartitionedRegion pr = (PartitionedRegion) getCache().getRegion(regionPath);
          PartitionedRegionDataStore ds = pr.getDataStore();
          if (ds == null) {
            return 0L;
          } else {
            return getSize(ds);
          }
        }
Creates partitioned regions in multiple vms and fully exercises the internal-only
getInternalPRDetails API on ResourceManager.
geode-core/src/distributedTest/java/org/apache/geode/cache/management/ResourceManagerDUnitTest.java