typescript-graphql-request incorrect nullable variable type for required input field with default

[ziimakc]

Describe the bug

For a schema:

type Query {
    test(
        a: Int # can be null
        b: Int = 1  # can be null if user pass null explicitly
        c: Int! # can't be null
        d: Int! = 1 # can't be null
    ): Int!
}

And query:

query test ($a: Int, $b: Int, $c: Int!, $d: Int) {
    test(a: $a, b: $b, c: $c, d: $d)
}

Generated QueryTestArgs is correct:

export type QueryTestArgs = {
  a?: InputMaybe<Scalars['Int']>;
  b?: InputMaybe<Scalars['Int']>;
  c: Scalars['Int'];
  d?: Scalars['Int'];
};

While types used in sdk is not:

export type TestQueryVariables = Exact<{
  a?: InputMaybe<Scalars['Int']>;
  b?: InputMaybe<Scalars['Int']>;
  c: Scalars['Int'];
  d?: InputMaybe<Scalars['Int']>; // this will allow to pass null that will be rejected by api
}>;

Your Example Website or App

https://codesandbox.io/s/cranky-kowalevski-98l6up

Expected behavior

export type TestQueryVariables = Exact<{
  a?: InputMaybe<Scalars['Int']>;
  b?: InputMaybe<Scalars['Int']>;
  c: Scalars['Int'];
  d?: Scalars['Int'] // we can allow to omit it which will be replaced by default, but it's not allowed to pass null
}>;

Platform

"graphql": 16.5.0
"@graphql-codegen/cli": "2.9.1"
"@graphql-codegen/typescript": "2.7.2"
"@graphql-codegen/typescript-operations": "2.5.2"
"@graphql-codegen/typescript-graphql-request": "4.5.2"

Codegen Config File

schema: schema.graphql
documents: document.graphql
generates:
  types.ts:
    plugins:
      - typescript
      - typescript-operations
      - typescript-graphql-request