java.lang.NullPointerException
        at org.netbeans.api.java.source.SourceUtils.getDependentRootsImpl(SourceUtils.java:722)
        at org.netbeans.api.java.source.SourceUtils.getDependentRoots(SourceUtils.java:712)
        at org.netbeans.modules.refactoring.java.RetoucheUtils.getClasspathInfoFor(RetoucheUtils.java:614)
        at org.netbeans.modules.refactoring.java.RetoucheUtils.getClasspathInfoFor(RetoucheUtils.java:595)
        at org.netbeans.modules.refactoring.java.RetoucheUtils.getClasspathInfoFor(RetoucheUtils.java:591)
        at org.netbeans.modules.refactoring.java.RetoucheUtils.getClasspathInfoFor(RetoucheUtils.java:674)
        at org.netbeans.modules.refactoring.java.ui.WhereUsedQueryUI.setParameters(WhereUsedQueryUI.java:133)
        at org.netbeans.modules.refactoring.spi.impl.ParametersPanel$Prepare.run(ParametersPanel.java:786)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:577)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1030)