@Test
void getHelper() {

    Helper<TestConnector> helper = this.manager.getHelper("test");
    assertNotNull(helper);
    assertEquals(this.testHelper, helper);
    assertNull(this.manager.getHelper("no-test"));
    TestHelper test = this.manager.getHelper("test", TestHelper.class);
    assertNotNull(test);
    assertEquals(this.testHelper, test);
    assertThrows(IllegalArgumentException.class, () -> this.manager.getHelper("test", BlankHelper.class));
    assertNull(this.manager.getHelper("no-test", TestHelper.class));
}