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/internal/ui/dialogs/DataItemBindingDialog.java
this.expression = expression;
		initExpression( );
	}
	public void setName( String name )
	{
		this.name = name;
		initName( );
	}
	private ComputedColumn newBinding;
	protected void createColumnName( ReportItemHandle input, String name )
	{
		newBinding = StructureFactory.newComputedColumn( input, name );
		setName( newBinding.getName( ) );
	}
	public void setInput( ReportItemHandle input )
	{
		this.input = input;
		setAggregateOns( DEUtil.getGroups( input ) );
		setDataTypes( ChoiceSetFactory.getDisplayNamefromChoiceSet( DATA_TYPE_CHOICE_SET ) );
		try
		{
			String bindingName = ( (DataItemHandle) input ).getResultSetColumn( );
			setTitle( bindingName == null ? NEW_DATAITEM_TITLE
					: EDIT_DATAITEM_TITLE );
			if ( bindingName != null )
			{
				bindingColumn = getInputBinding( input, bindingName );
			}
			if ( bindingColumn == null )
			{