Error: The 'DesignerType' attribute is invalid

During the development of a workflow custom activity, I added the code below to the action file.

<FieldBind Field="NewVersion" Text="" DesignerType="Boolean" Id="5"/>

Then, when trying to deploy this workflow activity, I got the error below from Visual Studio 2010:

Error occurred in deployment step 'Add Solution': Feature definition with Id ddaa9505-d30e-4c03-bcfd-e1ca7c6dbdda failed validation, file 'updateItemsByListviewSB_updateItemsByListviewSB\Elements\Elements.xml', line 17, character 47: The 'DesignerType' attribute is invalid - The value 'Boolean' is invalid according to its datatype 'String' - The Enumeration constraint failed.

In terms of the link here, I don't see any problem.  So I dig a little bit, and found the link here from MSDN.  Obviously there are some changes with the RTM version of SharePoint 2010.

After changing the "Boolean" to "Bool", the problem disappeared.

By the way, the changes are not just about "Boolean". There are quite a lot of minor changes with SharePoint 2010.