public function get_placeholders(): array {
		/**
		 * Filter the placeholders.
		 *
		 * @since 5.5.9
		 *
		 * @param array          $placeholders The placeholders.
		 * @param string         $id           The email ID.
		 * @param Email_Abstract $this         The email object.
		 */
		$placeholders = apply_filters( 'tec_tickets_emails_placeholders', $this->placeholders, $this->id, $this );

		/**
		 * Filter the placeholders for the particular email.
		 *
		 * @since 5.5.10
		 *
		 * @param array          $placeholders The placeholders.
		 * @param string         $id           The email ID.
		 * @param Email_Abstract $this         The email object.
		 */
		$placeholders = apply_filters( "tec_tickets_emails_{$this->slug}_placeholders", $placeholders, $this->id, $this );

		return $placeholders;
	}