What is the difference between

allAdmins(...): [Admin!]!

,

allAdmins(...): [Admin!]

, and

allAdmins(...): [Admin]!

?

#1: `[Admin!]!`:

[]

or

[admin1, admin2, ....]

#2: `[Admin!]`: #1 or

null

#3: `[Admin]!`: #1 or

[admin1, null, ...]