Source

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

public function get_collection_params() {
		$new_params            = array();
		$new_params['context'] = $this->get_context_param( array( 'default' => 'view' ) );
		$new_params['type']    = array(
			'description' => __( 'Limit results to taxonomies associated with a specific post type.' ),
			'type'        => 'string',
		);
		return $new_params;
	}