Bug 155365 Can not set data type to "date time" when editing "Data Item"
Description: Can not set data type to "date time" when editing "Data Item" Steps to reproduce: 1. Insert a data item to the layout 2. Name it and set the expression to "a = new Date()" 3. Select the data type to date time 4. Press ok Actual result: An Birt Exception is thrown out. Expected result: No NPE thrown out
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ColumnBindingDialog.java
public String getColumnText( Object element, int columnIndex )
		{
			if ( element == dummyChoice )
			{
				if ( columnIndex == 1 )
				{
					return INPUT_PROPMT;
				}
				return ""; 
			}
			ComputedColumnHandle handle = ( (ComputedColumnHandle) element );
			String text = null;
			switch ( columnIndex )
			{
				case 1 :
					text = handle.getName( );
					break;
				case 2 :
					text = ChoiceSetFactory.getDisplayNameFromChoiceSet( handle.getDataType( ),
							DATA_TYPE_CHOICE_SET );
					break;
				case 3 :
					text = handle.getExpression( );
					break;
				case 4 :
					String value = handle.getAggregrateOn( );
					String groupType = DEUtil.getGroupControlType( inputElement );
					if ( value == null )
					{
						if ( ExpressionUtil.hasAggregation( handle.getExpression( ) )