@Test
public void testFindFirstOfShouldNotReturnNull() throws ClassNotFoundException {

    //GIVEN
    Set<Class<? extends Object>> value = new HashSet<>();
    value.add(Object.class);
    given(packageBasedClassFinderCore.find(PACKAGE_NAME, INTERFACE_OR_CLASS)).willReturn(value);
    //WHEN
    Class<? extends Object> result = underTest.findFirstOf(INTERFACE_OR_CLASS, PACKAGE_NAME);
    //THEN
    assertNotNull(result);
}