@Documented @Retention(value=RUNTIME) @Target(value=TYPE) @Experimental(value=SPLITTABLE_DO_FN) public static @interface DoFn.BoundedPerElement
DoFn
 specifying that the DoFn performs a bounded amount of work per input element, so
 applying it to a bounded PCollection will produce also a bounded PCollection.
 It is an error to specify this on a non-splittable DoFn.