public function get_field_in_group( $field_group, $sub_field ) {
		if ( ! $field_group instanceof Field_Contract ) {
			$field_group = $this->get_field( $field_group );
		}

		if ( ! $field_group || 'group' !== $field_group->get_type() ) {
			return null;
		}

		$sub_fields = $field_group->prop( 'fields', [] );

		if ( ! array_key_exists( $sub_field, $sub_fields ) ) {
			return null;
		}

		return $this->get_new_field( $sub_fields[ $sub_field ], $field_group );
	}