Camel-Case relationship in include?

[endingman]

I have relationship like this in model:
public function sampleItems(){ //code }

1:
protected $availableIncludes = ['sampleItems'];
when I use include for item it will return 'sampleItems'.
when I use include for collection or paginator it will return 'sample_items'.
why not the same return?
2:

when I use include for item ,I can use like this:
protected $availableIncludes = ['sample_items'];
And it will return 'sample_items'.

when I use include for collection or paginator,I can not use like this:
protected $availableIncludes = ['sample_items'];
And it will get an error.

So how can I use a relationship of Camel-Case in the right way when I use include?

[specialtactics]

I am not sure tbh but I believe this is handled by League/Serealizer, not dingo.