checkNotNull(key);
    checkNotNull(value);
    int hash = hash(key);
    return segmentFor(hash).put(key, hash, value, false);
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable V putIfAbsent(K key, V value) {
    checkNotNull(key);
    checkNotNull(value);
    int hash = hash(key);
    return segmentFor(hash).put(key, hash, value, true);
  }

  @Override

        // Track creation time for rotation (only for non-archived keys)
        if (!sessionId.contains(".v")) {
            keyCreationTimes.put(sessionId, System.currentTimeMillis());
            keyVersions.putIfAbsent(sessionId, 0);
        }

        // Optionally store in KeyStore
        if (keyStore != null) {
            try {
                KeyStore.SecretKeyEntry keyEntry = new KeyStore.SecretKeyEntry(secretKey);

      L existing = locks.get(index);
      if (existing != null) {
        return existing;
      }
      L created = supplier.get();
      existing = locks.putIfAbsent(index, created);
      return MoreObjects.firstNonNull(existing, created);
    }

    @Override
    public int size() {
      return size;
    }
  }

  /** A bit mask were all bits are set. */

      ConcurrentMap<Signature, Method> map = Maps.newConcurrentMap();
      for (Method method : getVisibleMethods(cls)) {
        if (!Invokable.from(method).isStatic()) {
          map.putIfAbsent(new Signature(method), method);
        }
      }
      return map.values();
    }

    private ImmutableList<Method> getVisibleMethods(Class<?> cls) {

      ConcurrentMap<Signature, Method> map = Maps.newConcurrentMap();
      for (Method method : getVisibleMethods(cls)) {
        if (!Invokable.from(method).isStatic()) {
          map.putIfAbsent(new Signature(method), method);
        }
      }
      return map.values();
    }

    private ImmutableList<Method> getVisibleMethods(Class<?> cls) {

    if (existing != null) {
      return existing;
    }
    Map<E, LockGraphNode> created = createNodes(clazz);
    existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.putIfAbsent(clazz, created);
    return MoreObjects.firstNonNull(existing, created);
  }

  /**
   * For a given Enum type, creates an immutable map from each of the Enum's values to a

        // to generate a UID for the same object from multiple threads, but
        // that shouldn't be a problem.
        uid = counter.getAndIncrement();
        Integer alreadySet = uids.putIfAbsent(obj, uid);
        if (alreadySet != null) {
          uid = alreadySet;
        }
      }
      return uid;
    }

    @Override