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
{
							selectedColumnName = newName;
						}
					}
				}
				else
				{
					ComputedColumnHandle bindingHandle = ( (ComputedColumnHandle) element );
					if ( COLUMN_DATATYPE.equals( property ) )
					{
						bindingHandle.setDataType( dataTypes[( (Integer) value ).intValue( )].getName( ) );
					}
					else if ( COLUMN_EXPRESSION.equals( property ) )
					{
						if ( !( bindingHandle.getExpression( ) != null && bindingHandle.getExpression( )
								.equals( (String) value ) ) )
						{
							bindingHandle.setExpression( (String) value );
							String groupType = DEUtil.getGroupControlType( inputElement );
							if ( ExpressionUtil.hasAggregation( bindingHandle.getExpression( ) ) )
							{
								if ( groupType.equals( DEUtil.TYPE_GROUP_GROUP ) )
									bindingHandle.setAggregrateOn( ( (GroupHandle) DEUtil.getGroups( inputElement )
											.get( 0 ) ).getName( ) );
								else if ( groupType.equals( DEUtil.TYPE_GROUP_LISTING ) )
									bindingHandle.setAggregrateOn( null );
							}
							if ( !ExpressionUtil.hasAggregation( bindingHandle.getExpression( ) )
									|| groupType.equals( DEUtil.TYPE_GROUP_NONE ) )
							{