small example with uniform graphql mutation handling optional properties

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**Describe the issue**

Hi, I can't craft a uniform mutation using generated CRUD resolvers that can process optional properties.

Example that does work:

variables (phoneNumber is optional but provided):
```json
{"id": "1", "email": "not@us.ed", "name": "mame", "phoneNumber": "123456789"}

```
mutation:
```gql
mutation UpdateUser(
$id: String!
$email: String!
$name: String!
$phoneNumber: String
) {
updateUser(
where: { id: $id }
data: {
email: { set: $email }
name: { set: $name }
phoneNumber: { set: $phoneNumber }
}
) {
updatedAt
name
email
phoneNumber
}
}
```
Which sets the `phoneNumber` field, which is ok.

But when I then leave out the `phoneNumber` I get this error:
```
Argument data.phoneNumber of type NullableStringFieldUpdateOperationsInput needs at least one argument.
```

I would think it is possible to construct a uniform mutation that is idempotent, so we don't have to track what is optional and what is given and then have to adapt our mutation accordingly. (That would suk)

Start by reproducing the generated CRUD resolver mutation shown for updateUser, comparing the case where the optional phoneNumber variable is provided with the case where it is omitted. Trace how NullableStringFieldUpdateOperationsInput handles omitted properties and verify that the completed behavior permits a uniform mutation without changing the requested fields.

Written by the indexing model from the issue text.