message: Fixed NameValuePairProto reference
diff: @@ -279,7 +279,7 @@ message ValueProto {
  // Defines a union value in its serialized format.
  // The name is the discriminator from the union type.
  message UnionProto {
  - optional NamedValueProto choice = 1;
  + optional NameValuePairProto choice = 1;
  }
  // Defines a map in its serialized format.
  