public Set<PersistentMemberPattern> getRevokedIDs() {
    lock(false);
    try {
      // Return a copy of the set, because we modify it in place.
      return new HashSet<>(revokedMembers);
    } finally {
      unlock(false);
    }

  }
Get the set of members known to be revoked
geode-core/src/main/java/org/apache/geode/internal/cache/DiskInitFile.java