Bug 191089 cross tab Binding tab- Aggregate On field is shows incorrect field name
Cross tab-Binding under properties hows incorrect field for 'Aggregate On'. It show show similar to regular table binding 'Aggregate On' field. For example; instead of Location/country it should show either 'N/A' for table or 'Group Country' for any group.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
* 
	 * Return DesignElementHandle avaliable method's argument type name.
	 * 
	 * @param handle
	 *            DesignElementHandle.
	 * @param methodName
	 * @param argIdex
	 *            starts from 0.
	 * @return
	 */
	public static String getMethodArgumentType( DesignElementHandle handle,
			String methodName, int argIndex )
	{
		if ( handle instanceof DataSetHandle )
			return ReportDesignConstants.DATA_SET_ELEMENT; 
		if ( handle instanceof DataSourceHandle )
			return ReportDesignConstants.DATA_SOURCE_ELEMENT; 
		List methods = handle.getDefn( ).getLocalMethods( );
		for ( Iterator iter = methods.iterator( ); iter.hasNext( ); )
		{
			IMethodInfo method = ( (ElementPropertyDefn) iter.next( ) ).getMethodInfo( );
			if ( method.getName( ).equals( methodName ) )
			{
				Iterator argumentListIterator = method.argumentListIterator( );
				if ( argumentListIterator.hasNext( ) )
				{
					IArgumentInfoList argumentInfoList = (IArgumentInfoList) argumentListIterator.next( );
					int i = 0;
					for ( Iterator iterator = argumentInfoList.argumentsIterator( ); iterator.hasNext( ); i++ )
					{