<why are these defined multiple times in different classes ?
This is defined 2 times in CordovaSimManageDeviceDialog and CordovaSimRestartCallback - both classes from different plugins (org.jboss.tools.vpe.cordovasim & org.jboss.tools.cordavasim.eclipse). So, I could have defined it in the only place, but it would require Require-Bundle / Import-Package. We used to have the same approach for previous callbacks before reimplementation -  
just decided not to brake previous style and frankly don't know how to do it in a more neat way
<and why do you need a 15+ character long parameter delimiter when a simply space should be enough ?
I used to have space delimiter but this approach doesn't work. Parameters could contain spaces (start page, root folder), so I need something specific (see CordovaSimRestartCallback). About 15+ characters - just decided not to be stingy and provided meaningful delimiter :-)