java.io.IOException: cvc-complex-type.2.4.b: The content of element 'data' is not complete. One of '{"http://www.netbeans.org/ns/j2se-project/3":minimum-ant-version, "http://www.netbeans.org/ns/j2se-project/3":explicit-platform, "http://www.netbeans.org/ns/j2se-project/3":web-service-clients, "http://www.netbeans.org/ns/j2se-project/3":source-roots}' is expected.
   at org.netbeans.modules.project.uiapi.DefaultProjectOperationsImplementation$4$2.run(DefaultProjectOperationsImplementation.java:379)
   at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:122)
   at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:539)
   at org.netbeans.modules.project.uiapi.DefaultProjectOperationsImplementation$4.execute(DefaultProjectOperationsImplementation.java:374)
   at org.netbeans.modules.project.uiapi.DefaultProjectOperationsImplementation$6$1.run(DefaultProjectOperationsImplementation.java:670)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:602)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1084)