The file 'forms-1.3.0.jar' is used by the visual swing (or other) editor.
- Navigate to the folder eclipse is housed in.
- Using the search bar, search for "forms-1.3.0". Not the zipped folder, the jar file above it
- Drag it onto the project file with the exclamation mark.
Do the same thing with "miglayout15-swing.jar".
I don't know how to get rid of them, but if you're asking how to get rid of the exclamation mark, this is it.