public static GrpcClientBuilder builder(SessionProtocol protocol, EndpointGroup endpointGroup) {
        return builder(Scheme.of(GrpcSerializationFormats.PROTO, requireNonNull(protocol, "protocol")),
                       endpointGroup);
    }
Returns a new {@link GrpcClientBuilder} that builds the gRPC client that connects
to the specified {@link EndpointGroup} with the specified {@link SessionProtocol} and
{@link GrpcSerializationFormats#PROTO}.
grpc/src/main/java/com/linecorp/armeria/client/grpc/GrpcClients.java