//Dialog Code
//Assume I created a contentcomposite already

ComboViewer comboViewer = new ComboViewer(parent, SWT.READ_ONLY);        comboViewer.setContentProvider(ArrayContentProvider.getInstance());
comboViewer.setLabelProvider(new LabelProvider());       
comboViewer.setInput(importModel.getcViewerList()); //will get values for combo viewer

ListViewer listViewer = new ListViewer(parent);
 listViewer.setContentProvider(ArrayContentProvider.getInstance());
 listViewer.setLabelProvider(new LabelProvider());


//Model Class

public class TestModel {

    private Collection<String> testList = new ArrayList<>();

    private String testValue1;

    public Collection<String> gettestList() {
        return testList;
    }

    public void settestList(Collection<String> teslist) {
        this.vehicleClassesList = teslist;
    }
}