I am trying to add a radio button to the Activiti Explorer form but I have not succeeded. I searched on com.vaadin.ui but I do not find a radiobutton either. Thank you.
You will need to follow the following example to create a custom form renderer:
Creating a new form property in Activiti | Small steps with big feet
As for VAADIN, I believe you are looking for an OptionGroup.
Retrieving data ...