/**
* Supplies the value to be returned by each poll.
*
* <p>Note this <em>must</em> use generics, otherwise the return type of subsequent chained calls
* will (e.g. to {@link FeedConfig#onException(com.google.common.base.Function)} will return the
* wrong type.
*/
@SuppressWarnings("unchecked")
public <newS> FunctionPollConfig<newS, T> supplier(final Supplier<? extends newS> val) {
this.callable = Functionals.callable(checkNotNull(val, "supplier"));
return (FunctionPollConfig<newS, T>) this;
}
