Any encoding of the symbols?

Hi,

I have a struct in this format
```
type Response struct {
Url string `protobuf:"bytes,1,opt,name=url,json=url,proto3" json:"url,omitempty"`
XXX_NoUnkeyedLiteral struct{} `json:"-"`
XXX_unrecognized []byte `json:"-"`
XXX_sizecache int32 `json:"-"`
}
```

I set it as
```
return &Response{
Url: "https://abcd.com/&abcd"
}
```

When I make the request, I got this response
```
{
"url": "https://abcd.com/\u0026abcd"
}
```
The `\u0026` should be `&` here but I don't know why it appears to be encoded. I wonder whether that's what grpcurl does? Because I haven't found anything with my code which does the encoding...