static UnframedGrpcStatusMappingFunction of() {
        return (ctx, status, response) -> GrpcStatus.grpcStatusToHttpStatus(ctx, status);
    }
Return the default mapping function which follows the mapping rules defined in upstream Google APIs
<a href="https://github.com/googleapis/googleapis/blob/b2a7d2709887e38bcd3b5142424e563b0b386b6f/google/rpc/code.proto">
code.proto</a>.
grpc/src/main/java/com/linecorp/armeria/server/grpc/UnframedGrpcStatusMappingFunction.java