Using the following api which finds all the contexthub stores. Each store has it's own ValueMap.
Que. Using the api, how to add any new key:value to the store?
We are checking internally - we do not have any doc on this other then Javadocs.
Have you tried the setProperties method on the Store object? Store ("The Adobe AEM Quickstart and Web Application.")
Contexthub accepts JSON Data and you can use API to load json data. Where exactly do you want to API to load store?