public static boolean isColocationComplete(PartitionedRegion region) {
    Region prRoot = PartitionedRegionHelper.getPRRoot(region.getCache());
    PartitionRegionConfig config = (PartitionRegionConfig) prRoot.get(region.getRegionIdentifier());
    // Fix for bug 40075. There is race between this call and the region being concurrently
    // destroyed.
    if (config == null) {
      Assert.assertTrue(region.isDestroyed() || region.isClosed,
          "Region is not destroyed, but there is no entry in the prRoot for region " + region);
      return false;
    }
    return config.isColocationComplete();
  }
A utility to check to see if a region has been created on all of the VMs that host the regions
this region is colocated with.
geode-core/src/main/java/org/apache/geode/internal/cache/ColocationHelper.java