public boolean containsTombstoneGCVersions(Map<T, Long> regionGCVersions) {
    Long myVersion = regionGCVersions.get(myId);
    if (myVersion != null) {
      if (localGCVersion.get() < myVersion) {
        return false;
      }
    }
    synchronized (memberToGCVersion) {
      for (Map.Entry<T, Long> entry : regionGCVersions.entrySet()) {
        Long version = memberToGCVersion.get(entry.getKey());
        if (version == null || version < entry.getValue()) {
          return false;
        }
      }
    }
    return true;
  }
returns true if all of the GC versions in the given map have already been processed here
geode-core/src/main/java/org/apache/geode/internal/cache/versions/RegionVersionVector.java