api context /services/iscsi/targettoextent does not allow null value for iscsi_lunid

attempting to create a new targettoextent fails if iscsi_lunid is any non integer value (returned error: {"iscsi_lunid": ["Enter a whole number."]} API documentation states that Null is a valid value. without null it becomes a multistep process to indentify the currently mapped luns to the target before mapping a new one.