A DESCRIPTION OF THE PROBLEM :
The javaws.cfg.jauthenticator property must be set in a JNLP file to disable the built-in javaws HTTP authentication dialogue.
The property is not fully documented and the value you need is misleading. I would expect set the property to "false" to disable the authentication dialogue. Instead I had to set it to "true".
The code in com.sun.deploy.config.Config which tests the property is:
String value = "" + (!auth.equalsIgnoreCase("all") &&
p.setProperty (SEC_AUTHENTICATOR_KEY, value);
The value for SEC_AUTHENTICATOR_KEY becomes "false" if javaws.cfg.jauthenticator is set to "true" or "all".
This is confusing.
EXPECTED VERSUS ACTUAL BEHAVIOR :
Something - especially why the property needs to be set to "true", since the meaning cannot be changed in future releases
URL OF FAULTY DOCUMENTATION :