@Test
void composeToString() {

    final ToString<String> toString = string -> string;
    final ComposeToString<String, String, ToString<String>> composeToString =
            (ComposeToString<String, String, ToString<String>>)
                    ComposedUtil.composeToString(Function.identity(), toString);
    assertNotNull(composeToString.firstStep());
    assertNotNull(composeToString.secondStep());
    assertNull(composeToString.apply(null));
    assertNotNull(composeToString.apply("test"));
}