public static FindKV findKV(String regex, int keyGroup, int valueGroup) {
    return findKV(Pattern.compile(regex), keyGroup, valueGroup);
  }
@Test
  @Category(NeedsRunner.class)
  public void testKVFindNone() {

    PCollection<KV<String, String>> output =
        p.apply(Create.of("x y z")).apply(Regex.findKV("a (b) (c)", 1, 2));

    PAssert.that(output).empty();
    p.run();
  }