@type t() ::
  %Envoy.Extensions.Upstreams.Http.V3.HttpProtocolOptions.UseDownstreamHttpConfig{
    __unknown_fields__: [
      {field_number :: integer(), Protobuf.Wire.Types.wire_type(),
       value :: term()}
    ],
    http2_protocol_options: Envoy.Config.Core.V3.Http2ProtocolOptions.t() | nil,
    http3_protocol_options: Envoy.Config.Core.V3.Http3ProtocolOptions.t() | nil,
    http_protocol_options: Envoy.Config.Core.V3.Http1ProtocolOptions.t() | nil
  }