// if both fields are non-empty, they must have the same value. For backwards
  // compatibility, when namespace isn't specified in dataSourceRef,
  // both fields (dataSource and dataSourceRef) will be set to the same
  // value automatically if one of them is empty and the other is non-empty.
  // When namespace is specified in dataSourceRef,
  // dataSource isn't set to the same value and must be empty.