public HashSet<PersistentMemberPattern> getRevokedMembers() {
    synchronized (this) {
      return new HashSet<>(revokedMembers.keySet());
    }
  }
Add a new revocation listener

@param listener The revocation listener
@param recoveredRevokedMembers a set of members which the listener knows have been revoked
geode-core/src/main/java/org/apache/geode/internal/cache/persistence/PersistentMemberManager.java