@type t() ::
%Envoy.Extensions.Filters.Network.ThriftProxy.Filters.PayloadToMetadata.V3.PayloadToMetadata.FieldSelector{
__unknown_fields__: [
{field_number :: integer(), Protobuf.Wire.Types.wire_type(),
value :: term()}
],
child: t() | nil,
id: integer(),
name: String.t()
}