If this .gbb file is not in jar then CourseLab does not "know" about it, therefore it is not copied to "images" folder. But if you can change in Java-applet URL from where this file should be loaded to "../user/[your_file].gbb" then we have simple solution. Create "user" folder at the same level with "images" folder and place your .gbb files here. If "user" folder exists in module's folder then CourseLab will push this folder in published version as is.
If you cannot change URL in Java-applet then things will be a little bit worse. Then we should make this .gbb file the part of the module, for example, this file can be placed in some invisible object - object External File suits well. Insert this object on the same Frame with Java-applet, select your .gbb file as target file, and set object's Display parameter to "No" (in Format Object context menu). Then your .gbb file will be placed in "images" folder near the .jar, and will be included in published version automatically.
If this .gbb file is not in jar then CourseLab does not "know" about it, therefore it is not copied to "images" folder. But if you can change in Java-applet URL from where this file should be loaded to "../user/[your_file].gbb" then we have simple solution. Create "user" folder at the same level with "images" folder and place your .gbb files here. If "user" folder exists in module's folder then CourseLab will push this folder in published version as is.
If you cannot change URL in Java-applet then things will be a little bit worse. Then we should make this .gbb file the part of the module, for example, this file can be placed in some invisible object - object External File suits well. Insert this object on the same Frame with Java-applet, select your .gbb file as target file, and set object's Display parameter to "No" (in Format Object context menu). Then your .gbb file will be placed in "images" folder near the .jar, and will be included in published version automatically.