Java SE (Java Platform, Standard Edition)

I have an application which I want to deploy through a browser link to a JNLP file.
The link to the JNLP file is behind Basic Authentication; the JNLP and the JARS are also behind Basic Authentication.

Users have to login to go to the HTML page where they can click on the link to the JNLP file. Java Web Start then pops up an authentication window where the user has to login again. There is a checkbox suggesting that the authentication could be saved, but that does not work.

I (and my users) would like this second authentication to be skipped in some way, or at least the authentication data being saved as the checkbox suggests.

How can I achieve this?

BTW The application accesses web services, also behind Basic Authentication. The authentication for Java Web Start is re-used automatically for those webservices.