Mean { public static <NumT extends Number> Combine.AccumulatingCombineFn<NumT, CountSum<NumT>, Double> of() { return new MeanFn<>(); } private  Mean(); static Combine.Globally<NumT, Double> globally(); static Combine.PerKey<K, NumT, Double> perKey(); static Combine.AccumulatingCombineFn<NumT, CountSum<NumT>, Double> of();  }
@Test public void testMeanFn() throws Exception { testCombineFn(Mean.of(), Lists.newArrayList(1, 2, 3, 4), 2.5); }