message: test(ref): remove helper type, because upstream now contains it
diff: import * as mongoose from 'mongoose';
  import { assertion, getName } from '../../src/internal/utils';
  import { getModelForClass, isDocument, isDocumentArray, isRefType, prop, Ref } from '../../src/typegoose';
  -import { KeyStringAny } from '../../src/types';
  import { RefTestArrayTypesModel, RefTestBufferModel, RefTestModel, RefTestNumberModel, RefTestStringModel } from '../models/refTests';
  it('check generated ref schema for ObjectID _id', async () => {
  @@ -275,9 +274,6 @@ it('reference arrays should work with mongoose.Types.Array<Ref<T>>', async () =>
  expect(Array.from(found.array!.toObject())).toEqual([stringdoc._id, stringdoc._id]);
  });
  -/** // TODO: this "as" is because "SchemaType" currently has no "options" property */
  -type HelperSchemaType = mongoose.SchemaType & { options: KeyStringAny };
  -
  it('should map options correctly on an ref-array', async () => {
  const validateInner = jest.fn(() => true);
  const validateOuter = jest.fn(() => true);
  @@ -317,8 +313,7 @@ it('should map options correctly on an ref-array', async () => {
  expect(RefArrayOptionsMappingNestedModel.schema.path('dummy')).toBeInstanceOf(mongoose.Schema.Types.String);
  {
  - // TODO: this "as" is because "SchemaType" currently has no "options" property
  - const normalRef = schema.path('normalRef') as HelperSchemaType;
  + const normalRef = schema.path('normalRef');
  expect(normalRef).toBeInstanceOf(mongoose.Schema.Types.ObjectId);
  expect(normalRef.options.type).toEqual(mongoose.Schema.Types.ObjectId);
  @@ -326,8 +321,7 @@ it('should map options correctly on an ref-array', async () => {
  }
  {
  - // TODO: this "as" is because "SchemaType" currently has no "options" property
  - const normalRefArray = schema.path('normalRefArray') as HelperSchemaType;
  + const normalRefArray = schema.path('normalRefArray');
  expect(normalRefArray).toBeInstanceOf(mongoose.Schema.Types.Array);
  expect(normalRefArray.options.type).toBeInstanceOf(Array);
  @@ -337,8 +331,7 @@ it('should map options correctly on an ref-array', async () => {
  }
  {
  - // TODO: this "as" is because "SchemaType" currently has no "options" property
  - const validatedRef = schema.path('validatedRef') as HelperSchemaType;
  + const validatedRef = schema.path('validatedRef');
  expect(validatedRef).toBeInstanceOf(mongoose.Schema.Types.ObjectId);
  expect(validatedRef.options.type).toEqual(mongoose.Schema.Types.ObjectId);
  @@ -347,8 +340,7 @@ it('should map options correctly on an ref-array', async () => {
  }
  {
  - // TODO: this "as" is because "SchemaType" currently has no "options" property
  - const validatedRefArray = schema.path('validatedRefArray') as HelperSchemaType;
  + const validatedRefArray = schema.path('validatedRefArray');
  expect(validatedRefArray).toBeInstanceOf(mongoose.Schema.Types.Array);
  expect(validatedRefArray.options.type).toBeInstanceOf(Array);
  @@ -359,8 +351,7 @@ it('should map options correctly on an ref-array', async () => {
  }
  {
  - // TODO: this "as" is because "SchemaType" currently has no "options" property
  - const explicitDoubleRefArray = schema.path('explicitDoubleRefArray') as HelperSchemaType;
  + const explicitDoubleRefArray = schema.path('explicitDoubleRefArray');
  expect(explicitDoubleRefArray).toBeInstanceOf(mongoose.Schema.Types.Array);
  expect(explicitDoubleRefArray.options.type).toBeInstanceOf(Array);
  