Align the logic of isOptionalFactoryDependency internal utility

[micalevisk]

Is there an existing issue that is already proposing this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe it

at @nestjs/common we have a x is OptionalFactoryDependency with the following logic:

nest/packages/common/module-utils/utils/get-injection-providers.util.ts

Lines 14 to 18 in 7d62aad

	function isOptionalFactoryDependency(
	x: InjectionToken | OptionalFactoryDependency,
	): x is OptionalFactoryDependency {
	return !!((x as any)?.token && !(x as any)?.prototype);
	}

but at @nestjs/core we have a x is OptionalFactoryDependency with a bit different logic:

nest/packages/core/injector/injector.ts

Lines 346 to 350 in 7d62aad

	const isOptionalFactoryDep = (
	item: InjectionToken | OptionalFactoryDependency,
	): item is OptionalFactoryDependency =>
	!isUndefined((item as OptionalFactoryDependency).token) &&
	!isUndefined((item as OptionalFactoryDependency).optional);

I can't tell if this was intentional or not. Thus, I can't tell which function has the correct logic.

Describe the solution you'd like

Ensure that both isOptionalFactoryDependency and isOptionalFactoryDep have the same logic, as we don't want to expose that internal utility from outside of @nestjs/* packages.

Teachability, documentation, adoption, migration strategy

N/A

What is the motivation / use case for changing the behavior?

I believe that OptionalFactoryDependency should be just one thing.

Also, 3rd-party packages might want to reuse that logic (like nestjs-spelunker here: https://github.com/jmcdo29/nestjs-spelunker/blob/3cf07cbaef306e885eb031ad46f979cc7497dfd1/src/exploration.module.ts#L149-L153).

[kamilmysliwiec]

Sounds good to me. Would you like to create a PR for this issue?

[kamilmysliwiec]

let's track this here #14175