Render regular element in a form should not duplicate container ID.

I've just attempted to replicate this on 10.2.4

I created a custom module using drush generate simple:form and installed

In the form I created the following insight the generated buildForm method

    $form['acontainer'] = [
	    '#type' => 'container',
	    '#title' => $this->t('Container'),
    ];

    $form['container']['atextfield'] = [
	    '#type' => 'textarea',
	    '#title' => 'one',
	    '#required' => TRUE,
    ];

When I inspect the elements on the page rendered I see a control with an id 'edit-atextfield' which has a wrapper div with id 'edit-acontainer'

If this doesn't demonstrate the problem please include some clear steps to reproduce.