static boolean isProtobuf(@Nullable MediaType contentType) {
        return contentType == null ||
               contentType.is(MediaType.PROTOBUF) ||
               contentType.is(X_PROTOBUF) ||
               contentType.is(MediaType.OCTET_STREAM);
    }
Creates an instance with the specified {@link Parser} and {@link ExtensionRegistry}.
protobuf/src/main/java/com/linecorp/armeria/server/protobuf/ProtobufRequestConverterFunction.java