SerializationException on RPC call when providing List from store.getModifiedRecords

Hi
I am working with editable grid and i need to pass modified store records through RPC service.
I am getting SerializationException on RPC call.

I am simply passing list to following method..

Code:

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reEditorServiceAsync.setReportColumns(record,new AsyncCallback<List<ReportColumn>>()

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It gives serializationException , I am struggling here since last 2 days , can any one please help me out?