In current JDK9 (b108) if APIDialog is called without all-permissions (which it usually is), from a jnlp application where the jnlp file has no href, an access denied exception will be thrown from AppInfo.getJNLPFromUnknownSource(), when trying to get string to use in dialog.

use example below from JDK-6872847:
"javaws http://oklahoma.us.oracle.com/www/tests/1.9.0/6972847/TestNewSocket.jnlp"