/guava/android/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
this.delay = null;
this.delay = delay;
return new ReschedulableCallable(service, executor, runnable).reschedule(); } protected static final class Schedule { private final long delay; private final TimeUnit unit; public Schedule(long delay, TimeUnit unit) { <extra_id_0> this.unit = checkNotNull(unit); } } protected abstract Schedule getNextSchedule() throws Exception; } }