@Test public void parse_valuesAreRequired() {

  for (String missingValue : Arrays.asList("k1", "k1  ", "k1=v1,k2", "k1   ,k2=v1")) {
    assertThatThrownBy(() -> entrySplitter.parse(parseIntoMap, map, missingValue))
        .isInstanceOf(IllegalArgumentException.class)
        .hasMessage("Invalid input: missing key value separator '='");
  }
  assertThat(map.isEmpty());
}