Combine.GroupedValues javadoc code snippet does not work

PCollection<KV<String, Integer>> pc = ...;
PCollection<KV<String, Iterable<Integer>>> groupedByKey = pc.apply( new GroupByKey<String, Integer>());
PCollection<KV<String, Integer>> sumByKey = groupedByKey.apply( Combine.<String, Integer>groupedValues( new Sum.SumIntegerFn()));

PCollection<KV<String, Integer>> pc = ...;
PCollection<KV<String, Iterable<Integer>>> groupedByKey = pc.apply(GroupByKey.create());
PCollection<KV<String, Integer>> sumByKey = groupedByKey.apply(Combine.groupedValues(Sum.ofIntegers()));