This feature is experimental. It may be changed or removed in a future version without prior notice or deprecation.
Builds an URL string from the given base URL and
this up.Params instance as a query string.
The base URL may or may not already contain a query string. The
additional query string will be joined with an & or ? character accordingly.
The base URL that will be prepended to this up.Params object as a query string.
The built URL.