Module field_update 

Three-state wrapper for nullable input fields.

GraphQL distinguishes between an omitted field (“don’t change this”) and an explicit null (“clear this field”). Option<T> + skip_serializing_if can only express the first. MaybeUndefined<T> carries both, so generated input types can drive the Linear API faithfully without hand-rolled JSON patches on the consumer side.

Codegen emits nullable input fields as:

#[serde(default, skip_serializing_if = "MaybeUndefined::is_undefined")]
pub lead_id: MaybeUndefined<String>,

Consumers choose one of:

Intent	Value	Wire form
Leave unchanged	MaybeUndefined::Undefined	field omitted
Clear on the server	MaybeUndefined::Null	"field": null
Set to a value	MaybeUndefined::Value(v)	"field": v

Enums

MaybeUndefined

A three-state field value: undefined (omitted), null (explicit clear), or a concrete value.