Checkboxes in grid field settings not working

[gb-lin]

I noticed this while developing a fieldtype add-on. If the field is used in a grid field, the "checkboxes" field settings will not save when being created. I verified this by testing EE native "URL" fieldtype.

Steps to reproduce:

1. Create a grid field
2. Select URL as the first column
3. Change the Allowed URL Schemes settings
4. Save
5. You'll see that the Allowed URL Schemes is not saved with the selected choices
6. Change the Allowed URL Schemes again and save
7. You'll then see the Allowed URL Schemes being saved correctly

I think the React script is not properly appending the new values when the field is not yet created.