Empty String with Java Web Start

Java Web Start JNLP doesn't allow us to pass empty string or spaces as an argument. There are valid cases to pass them as arguments. I don't know why it's not allowed.

This is the exception I got.

BadFieldException[ The field  has an invalid value: ,]
   at com.sun.javaws.jnl.XMLFormat$8.visitElement(XMLFormat.java:549)
   at com.sun.javaws.jnl.XMLUtils.visitElements(XMLUtils.java:258)
   at com.sun.javaws.jnl.XMLFormat.buildApplicationDesc(XMLFormat.java:545)
   at com.sun.javaws.jnl.XMLFormat.parse(XMLFormat.java:99)
   at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(LaunchDescFactory.java:48)
   at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(LaunchDescFactory.java:60)
   at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(LaunchDescFactory.java:117)
   at com.sun.javaws.Main.launchApp(Main.java:182)
   at com.sun.javaws.Main.main(Main.java:136)