V3 how to add a block?

In V2, placing a block in the …/customer/addon//blocks/block_name.tpl file would allow the block to be seen and incorporated into the block manager.

Under V3 this doesn't seem to work. The subscribe.tpl file within the news_and_emails addon is now in a sub directory named static_templates. However, placing the block for my addon in this subdirectory doesn't seem to pick it up either.

I note that in addons/exim that they have cs-cart addon templates hard coded into the XML schema for exporting/importing the block schema.

So how does one make a block visible to the block manager in V3 as an addon (I.e. if it's present and active it is picked up and if not, it isn't)? I can't even find where the static_templates directory is referenced in the source code!

Just for other's information, apparently now you have to do it via schema post processing. I.e. addons//schemas/block_manger/blocks.post.php file.

See what's used in the banners addon for a simple example.