Java Web Start usage: javaws [run-options] <jnlp-file>

It indicates that <jnlp-file> is required in this syntax, otherwise, the Java Web Start usage dialog should be displayed

but testing with JDK9-b32 promotion on windows from the command line:

javaws -offline ---> correctly displaying the Java Web Start usage dialog
javaws -system --> incorrectly not displaying Java Web Start usage dialog. In this case, it tries to launch (probably the null jnlp file) and fail silently

Based on the syntax, we should display Java Web Start usage dialog if user only executes:
javaws -system
(as in the case of javaws -offline)