How to upload fies to Knowledge center via Content Service

I am working on a plugin creation that uploads a file to Knowledge center from your system
i know that i have to use contentService
but in contentService their is function named "upload(Document doc, java.lang.Integer unique)" which returns ContentOutputStream instance
but i am unable to understand how the document is getting saved into Knowledge center.
Anyone please help struck in this for a while

Thanks in advance

OriginalPostID-235089

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