Before we close the book on our custom block plugin, though, let's take a look at how we can add a configuration form to it. This way, we can practice using some more Form API elements and see how we can store and use block configuration.
Even though our functionality is complete (for the moment), let's imagine that we need a Boolean-like control on our block configuration so that when an admin places the block, they can toggle something and that value can be used in the build() method. We can achieve this with three to four methods on our plugin class.
First, we will need to implement the defaultConfiguration() method, in which we can describe the items of configuration that we are storing for this block and the default ...
