Is this supported by 16.2? Is there a sample or documentation about this?
Creating Discussions and Topics is not currently supported.
I would be a simple matter for a skilled Oscripter to create a REST API Extension to support this. My guess is that it hasn't been done because there isn't enough demand to productize it. Besides myself, there are about a dozen solid Oscripters here who could probably do this as a custom module.
-Hugh Ferguson
PS. I've done this in the past - I wrote a Forms extension way back when, as well as a REST API Extension for workflow.
As of 16.2.8, forums (type:123469) and their topics/replies (type:123470) can be created via the REST API using a POST operation.For topics/replies, the content is passed via the topic_text parameter.