guava/src/com/google/common/collect/ImmutableMap.java
@Override
  public ImmutableCollection<V> values() {
    ImmutableCollection<V> result = values;
    return (result == null) ? values = createValues() : result;
  }
@Override
  public ImmutableCollection<V> values() {
    ImmutableCollection<V> result = values;
    return (result == null) ? values = createValues() : result;
  }
Returns an immutable collection of the values in this map, in the same order that they appear
in {@link #entrySet}.