t() :: %Protobuf.MessageProps{
  enum?: boolean(),
  extendable?: boolean(),
  field_props: %{optional(integer()) => Protobuf.FieldProps.T},
  field_tags: %{optional(atom()) => integer()},
  field_tags_str: %{optional(String.t()) => integer()},
  map?: boolean(),
  oneof: [{atom(), non_neg_integer()}],
  ordered_tags: [integer()],
  repeated_fields: [atom()],
  syntax: atom(),
  tags_map: %{optional(integer()) => integer()}
}