Initialize the object. Invoked upon construction and wake up.
Overrides EntityNG::init
protected function init() {
parent::init();
// We unset all defined properties except theme, so magic getters apply.
// $this->theme is a special use-case that is only used in the lifecycle of
// adding a new block using the block library.
unset($this->id);
unset($this->info);
unset($this->revision_id);
unset($this->log);
unset($this->uuid);
unset($this->type);
unset($this->new);
}