pub fn origin(self, origin: Uri) -> Self {
        Endpoint {
            origin: Some(origin),
            ..self
        }
    }
Set a custom origin.

Override the `origin`, mainly useful when you are reaching a Server/LoadBalancer
which serves multiple services at the same time.
It will play the role of SNI (Server Name Indication).

```
# use tonic::transport::Endpoint;
# let mut builder = Endpoint::from_static("https://proxy.com");
builder.origin("https://example.com".parse().expect("http://example.com must be a valid URI"));
// origin: "https://example.com"
```
tonic/src/transport/channel/endpoint.rs