With this build property definitions of a build configurations get an additional "Spec" attribute.
This property "meta" information is then used to display the property in the "Run custom build" dialog.
It can be used to:
- specify property presentation (checkbox, drop-down, validation for valid integer value)
- specify display text to use instead of property name
- mark property as mandatory (user needs to specify it's value before running a build)
- mark property as hidden (the property will not appear in cutom run dialog)
These settings are configred via a specially-formatted string described in the comment of the original issue.