core/play/src/main/java/play/mvc/Results.java
public static Result permanentRedirect(Call call) {
    return new Result(PERMANENT_REDIRECT, Collections.singletonMap(LOCATION, call.path()));
  }
public static Result permanentRedirect(Call call) {
    return new Result(PERMANENT_REDIRECT, Collections.singletonMap(LOCATION, call.path()));
  }
Generates a 308 Permanent Redirect result.

@param call Call defining the url to redirect (typically comes from reverse router).
@return the result