Best approach to create rest url to call external api in Java and SpringBoot

I'm working in a SpringBoot project where I'm developing a rest endpoint which will receive a few parameters and based on these parameters I will create a uri and I'll call another external endpoint to retrieve an image.

Right now I have a rest controller with the following endpoint:

 @GetMapping(value = "/{param1}/{param2}/{param3}/{param4}", produces = MediaType.IMAGE_JPEG_VALUE)
    public byte[] getImageryBaseMap(@PathVariable("param1") Long param1, @PathVariable("param2") Long param2,
                                    @PathVariable("param3") Long param3, @PathVariable("param4") Long param4)
    throws IOException{
        //calls my service
        return myService.getMyMethod(param1, param2, param3, param4);
    }

On myService class I make the call to an external endpoint.

 public byte[] retrieveImageryBaseMap(Long param1,  Long param2, Long param3, Long param4){
        String url = "https://host-name:6443/external/Image/export?bbox="+ param1 +"%" + param2+ "+%"+ param3 + "%" + param4 +"&format=png&f=image";

       // here I call the external api endpoint to retrieve an image
        byte[] image = getImage(url);
        return image;
    }

My questions would be:

1) What is the best approach/practices to manage creating the url above? I basically hardcoded almost all the url above just replacing the values by the parameters coming from the method retrieveImageryBaseMap . Would like to know if there's a better approach for that or if it's ok.

2)I also hardcoded the host name and the port in the url String url = "https://host-name:6443/external/Image/export?bbox="+ param1 +"%" + param2+ "+%"+ param3 + "%" + param4 +"&format=png&f=image"; Right now I'm just testing this using the dev host-name, but in production the host name and port will be different. So also would like to ask the best approach/practice to manage the host name in the url? Should I hardcoded like that or use a different approach?

Guys much appreciate any help, I'm working by myself and unfortunately don't have a mentor to ask those sort of questions and got stuck here.

Cheers!