EDIT

package eu.etaxonomy.taxeditor.navigation.navigator.dnd;

import java.util.ArrayList;

import java.util.List;

import org.eclipse.jface.viewers.IStructuredSelection;

import org.eclipse.swt.dnd.DragSourceEvent;

import org.eclipse.swt.dnd.Transfer;

import org.eclipse.ui.navigator.CommonDragAdapterAssistant;

import eu.etaxonomy.cdm.model.taxon.TaxonNode;

import eu.etaxonomy.taxeditor.dnd.transfer.TaxonNodeTransfer;

public class TaxonNavigatorDragAdapterAssistant extends

		CommonDragAdapterAssistant {

	@Override

	public Transfer[] getSupportedTransferTypes() {

		return new Transfer[] { TaxonNodeTransfer.getInstance() };

	}

	@Override

	public boolean setDragData(DragSourceEvent event,

			IStructuredSelection selection) {

		boolean setDataSuccess = false;

		List<TaxonNode> taxonNodes = new ArrayList<TaxonNode>();

		for (Object object : selection.toList()){

			if(object instanceof TaxonNode){

				taxonNodes.add(((TaxonNode) object));

				setDataSuccess = true;

			}

		}

		if (TaxonNodeTransfer.getInstance().isSupportedType(

				event.dataType)) {

			event.data = taxonNodes.toArray(new TaxonNode[taxonNodes.size()]);

		}

		return setDataSuccess;

	}

}