java.lang.NullPointerException
	at org.jlinda.nest.gpf.SubtRefDemOp.constructTargetMetadata(SubtRefDemOp.java:311)
	at org.jlinda.nest.gpf.SubtRefDemOp.initialize(SubtRefDemOp.java:146)
Caused: org.esa.snap.core.gpf.OperatorException
	at org.jlinda.nest.gpf.SubtRefDemOp.initialize(SubtRefDemOp.java:151)
	at org.esa.snap.core.gpf.internal.OperatorContext.initializeOperator(OperatorContext.java:486)
	at org.esa.snap.core.gpf.internal.OperatorContext.getTargetProduct(OperatorContext.java:273)
	at org.esa.snap.core.gpf.Operator.getTargetProduct(Operator.java:387)
	at org.esa.snap.core.gpf.GPF.createProductNS(GPF.java:318)
	at org.esa.snap.core.gpf.GPF.createProduct(GPF.java:293)
	at org.esa.snap.core.gpf.GPF.createProduct(GPF.java:272)
	at org.esa.snap.graphbuilder.rcp.dialogs.SingleOperatorDialog.createTargetProduct(SingleOperatorDialog.java:175)
[catch] at org.esa.snap.graphbuilder.rcp.dialogs.SingleOperatorDialog.onApply(SingleOperatorDialog.java:291)
	at org.esa.snap.ui.AbstractDialog.lambda$initUI$6(AbstractDialog.java:523)
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.awt.EventQueue.access$500(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)