question: invoked just as the operator functions is called to bind two operations together into a new observable and the return value is used as the lifted function this can be used to decorate or replace the operator instance or just perform extralogging , metrics and other such things and pass-thru the onsubscribe . concode_field_sep PlaceHolder placeHolder concode_field_sep OnSubscribe<T> onCreate concode_elem_sep Throwable onSubscribeError concode_elem_sep Subscription onSubscribeReturn concode_elem_sep OnSubscribe<T> onSubscribeStart
target: Operator < ? extends R , ? super T > function ( final Operator < ? extends R , ? super T > arg0 ) { return arg0 ; }