* to create the viewer and initialize it.
*/
public void createPartControl(Composite parent) {
viewer = new TreeViewer(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL);
drillDownAdapter = new DrillDownAdapter(viewer);
model = new JavaToBpelMappingModel();
viewer.setContentProvider(model);
viewer.setLabelProvider(model);
viewer.setInput(getViewSite());
model.addMappingChangedListener(this);
}