Searching the codebase I found only one usage of the
`ProcessorTopologyTestDriver` with `getKeyValueStore()` (or
`getStateStore()`) [0], and that usage only gets from store. Perhaps the
JavaDoc suggests something that cannot actually be done?
The obvious workaround is to get data into the store vi
I am trying to `put()` to a KeyValueStore that I got from
ProcessorTopologyTestDriver#getKeyValueStore() as part of setup for a test.
The JavaDoc endorses this use-case:
* This is often useful in test cases to pre-populate the store before
the test case instructs the topology to
* {@link
