NPE exporting a report virtualization and sub reports

[agarrison]

I have a report that contains a subreport in the detail section.  It renders fine, until I try to use swap file virtualization.  Then I get a null pointer exception.

java.lang.NullPointerException
    at java.lang.reflect.Array.newArray(Native Method)
    at java.lang.reflect.Array.newInstance(Array.java:70)
    at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1670)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1344)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
    at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:500)
    at net.sf.jasperreports.engine.base.JRBaseDataset.readObject(JRBaseDataset.java:356)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
    at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:500)
    at net.sf.jasperreports.engine.base.JRBaseReport.readObject(JRBaseReport.java:799)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
    at java.util.HashMap.readObject(HashMap.java:1184)
    at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
    at net.sf.jasperreports.engine.virtualization.VirtualizationInput.readJRObject(VirtualizationInput.java:120)
    at net.sf.jasperreports.engine.virtualization.VirtualizationInput.readJRObject(VirtualizationInput.java:105)
    at net.sf.jasperreports.engine.fill.JRTemplatePrintImage.readVirtualized(JRTemplatePrintImage.java:538)
    at net.sf.jasperreports.engine.virtualization.SerializableSerializer.read(SerializableSerializer.java:119)
    at net.sf.jasperreports.engine.virtualization.SerializableSerializer.read(SerializableSerializer.java:35)
    at net.sf.jasperreports.engine.virtualization.VirtualizationInput.readJRObject(VirtualizationInput.java:137)
    at net.sf.jasperreports.engine.virtualization.VirtualizationInput.readJRObject(VirtualizationInput.java:105)
    at net.sf.jasperreports.engine.base.VirtualElementsData.readVirtualized(VirtualElementsData.java:179)
    at net.sf.jasperreports.engine.virtualization.SerializableSerializer.read(SerializableSerializer.java:119)
    at net.sf.jasperreports.engine.virtualization.SerializableSerializer.read(SerializableSerializer.java:35)
    at net.sf.jasperreports.engine.virtualization.VirtualizationInput.readJRObject(VirtualizationInput.java:137)
    at net.sf.jasperreports.engine.virtualization.VirtualizationInput.readJRObject(VirtualizationInput.java:105)
    at net.sf.jasperreports.engine.util.VirtualizationSerializer.readData(VirtualizationSerializer.java:136)
    at net.sf.jasperreports.engine.util.SwapFileVirtualizerStore.retrieve(SwapFileVirtualizerStore.java:137)
    at net.sf.jasperreports.engine.fill.StoreVirtualizer.pageIn(StoreVirtualizer.java:62)
    at net.sf.jasperreports.engine.fill.JRAbstractLRUVirtualizer.requestData(JRAbstractLRUVirtualizer.java:536)
    at net.sf.jasperreports.engine.base.ElementsBlock.ensureData(VirtualizableElementList.java:463)
    at net.sf.jasperreports.engine.base.ElementsBlock.ensureDataAndTouch(VirtualizableElementList.java:432)
    at net.sf.jasperreports.engine.base.ElementsBlock.get(VirtualizableElementList.java:283)
    at net.sf.jasperreports.engine.base.VirtualizableElementList.get(VirtualizableElementList.java:96)
    at net.sf.jasperreports.engine.base.VirtualizableElementList.get(VirtualizableElementList.java:54)
    at java.util.AbstractList$Itr.next(AbstractList.java:358)