Array of nullable strings generates wrong annotation

[vsouz4]

the spec:

    SomeObject:
      type: object
      required:
        - someList
      properties:
        someList:
          type: array
          items:
            $ref: '#/components/schemas/SomeNullableString'
...
    SomeNullableString:
      type: string
      nullable: true

generates code like:

/**
  * @return string|null[]
  */
public function getSomeList(): array
{
    return $this->someList;
}