Could not unlock file inside Application contents For using RoboVM on OSX, I need to edit a file called info.plist, which resides inside the contents of the application called Android Studio.

Last year I managed to edit the file for Android Studio 1.5 (right image), but I now installed Android Studio 2.13 and I didn't succeed (left image).

It seems that the contents of this application are read only. How do I edit this file? I only need to change one value.
Assuming you're an admin you can add write permission to the group using the chmod command:

sudo chmod g+w /path/to/info.plist


Update:  Turns out they were launching the application directly from the disk image, which was likely mounted as read-only. Copying it to the local disk lets you make changes like this.