Source

File: wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php

public function __construct( $parent_post_type ) {
		$this->parent_post_type  = $parent_post_type;
		$this->namespace         = 'wp/v2';
		$this->rest_base         = 'revisions';
		$post_type_object        = get_post_type_object( $parent_post_type );
		$this->parent_base       = ! empty( $post_type_object->rest_base ) ? $post_type_object->rest_base : $post_type_object->name;
		$this->parent_controller = $post_type_object->get_rest_controller();

		if ( ! $this->parent_controller ) {
			$this->parent_controller = new WP_REST_Posts_Controller( $parent_post_type );
		}
	}