// presented as-is to a reader.
  // +optional
  optional string message = 2;

  // The field of the resource that has caused this error, as named by its JSON
  // serialization. May include dot and postfix notation for nested attributes.
  // Arrays are zero-indexed.  Fields may appear more than once in an array of
  // causes due to fields having multiple errors.
  // Optional.
  //
  // Examples: