guava/src/com/google/common/graph/ImmutableValueGraph.java
@Deprecated
  public static <N, V> ImmutableValueGraph<N, V> copyOf(ImmutableValueGraph<N, V> graph) {
    return checkNotNull(graph);
  }
@Deprecated
  public static <N, V> ImmutableValueGraph<N, V> copyOf(ImmutableValueGraph<N, V> graph) {
    return checkNotNull(graph);
  }
Simply returns its argument.

@deprecated no need to use this