NullPointerException when starting from signed JNLP file with non-standard VM args

FULL PRODUCT VERSION :
java version "1.8.0_92"
Java(TM) SE Runtime Environment (build 1.8.0_92-b14)
Java HotSpot(TM) Client VM (build 25.92-b14, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
Starting a webstart application gives a NullPointerException on the client if the file contains Java 9-style VM arguments (-addmods thing for example, instead of -Xarg=value)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Produce a small webstart application
2. Make sure the JNLP file has <j2se version="1.6+" max-heap-size="512m" java-vm-args="-ea -addmods java.se.ee"/> in it
3. Sign the JNLP file and the JAR file
4. Launch the application

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The application should launch

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NullPointerException
at com.sun.javaws.JnlpxArgs.execProgram(Unknown Source)
at com.sun.javaws.Launcher.relaunch(Unknown Source)
at com.sun.javaws.Launcher.prepareResources(Unknown Source)
at com.sun.javaws.Launcher.prepareAllResources(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.launch(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
test.jnlp
======

<?xml version="1.0" encoding="utf-8"?>
<jnlp spec="6.0+" codebase="http://jfkweb.cib.net/webstart" href="test.jnlp">
  <information>
    <title>Test app</title>
    <vendor>Anon</vendor>
    <offline-allowed/>
  </information>
  <security>
      <all-permissions/>
  </security>
  <update check="always" policy="always" />
  <resources>
    <j2se version="1.6+" max-heap-size="512m" java-vm-args="-ea -addmods java.se.ee"/>
    <jar href="test.jar" main="true"/>
  </resources>

  <application-desc main-class="Toto"/>
</jnlp>

Toto.java
=========

public class Toto {
  public static void main(String... argv) throws Exception {
    System.out.println("Success.");
  }
}


---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Add an extra line to the JNLP file so that the Java 9-style arguments are only taken into account for jdk > 8