How to extract sketch object through regular API

We are looking for ways to fetch theta sketch object through API. We want to implement this feature in our own druid cluster. Can someone have some advise?

The issue names no file or test; start by locating Druid's regular API entry points and the code handling theta sketches. Clarify the desired extraction format and endpoint behavior first, then define completion as a usable way to fetch the theta sketch object through the API.

Written by the indexing model from the issue text.