The operators of fromCallable, fromAction and fromRunnable in the reactive classes could use an <dt><b>Error handling:</b></dt> section in the JavaDocs describing the regular and canceled/disposed behavior.

If the {@link Callable/Action/Runnable} throws an exception/exception/unchecked exception, the respective {@link Throwable} is delivered to the downstream via {@link Subscriber/Observer/.../#onError()}, except when the downstream has canceled/disposed this {@code Flowable/Observable/Single/Maybe/Completable} source. In this latter case, the Throwable is delivered to the global error handler via {@link RxJavaPlugins#onError(Throwable)} as {@link io.reactivex.exceptions.UndeliverableException UndeliverableException}.