public Collection<DLockToken> getTokens() {
    synchronized (tokens) {
      return Collections.unmodifiableCollection(tokens.values());
    }
  }
Returns an unmodifiable collection backed by the values of the DLockToken map for testing
purposes only. Synchronizes on tokens map.

@return an unmodifiable collection of the tokens map values
geode-core/src/main/java/org/apache/geode/distributed/internal/locks/DLockService.java