The ActivityPub specification does not have an example of the "sharedInbox" field in use.

Although it does say "An optional endpoint..." — I suspect a lot of people won't know (with confidence) that it can go under the "endpoints" field. For example:

"endpoints": {
"sharedInbox": "https://social.example/inbox"
},

Especially if the person is still trying to understand ActivityPub, and isn't aware of the "endpoints" field yet.

sharedInbox

An optional endpoint used for wide delivery of publicly addressed activities and activities sent to followers. sharedInbox endpoints SHOULD also be publicly readable OrderedCollection objects containing objects addressed to the Public special collection. Reading from the sharedInbox endpoint MUST NOT present objects which are not addressed to the Public endpoint.
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