// Verify utility class design pattern compliance

        // 1. Class should be final (or have private constructor)
        Constructor<?>[] constructors = SystemUtil.class.getDeclaredConstructors();
        assertEquals("Should have exactly one constructor", 1, constructors.length);
        assertTrue("Constructor should be private", java.lang.reflect.Modifier.isPrivate(constructors[0].getModifiers()));

        // Verify utility class design pattern compliance

        // 1. Class should have protected constructor
        Constructor<?>[] constructors = ThreadDumpUtil.class.getDeclaredConstructors();
        assertEquals("Should have exactly one constructor", 1, constructors.length);
        assertTrue("Constructor should be protected", java.lang.reflect.Modifier.isProtected(constructors[0].getModifiers()));

        factories.add(factory);
      }
    }
    if (!Modifier.isAbstract(type.getRawType().getModifiers())) {
      for (Constructor<?> constructor : type.getRawType().getDeclaredConstructors()) {
        Invokable<T, T> invokable = type.constructor(constructor);
        if (!invokable.isPrivate() && !invokable.isSynthetic()) {
          factories.add(invokable);
        }
      }
    }

        // 2. Should have exactly one private constructor
        Constructor<?>[] constructors = WebApiUtil.class.getDeclaredConstructors();
        assertEquals("Should have exactly one constructor", 1, constructors.length);
        assertTrue("Constructor should be private", java.lang.reflect.Modifier.isPrivate(constructors[0].getModifiers()));

        // 2. Should have exactly one private constructor
        Constructor<?>[] constructors = KuromojiCSVUtil.class.getDeclaredConstructors();
        assertEquals("Should have exactly one constructor", 1, constructors.length);
        assertTrue("Constructor should be private", java.lang.reflect.Modifier.isPrivate(constructors[0].getModifiers()));

   * minimalVisibility}.
   */
  public void testConstructors(Class<?> c, Visibility minimalVisibility) {
    for (Constructor<?> constructor : c.getDeclaredConstructors()) {
      if (minimalVisibility.isVisible(constructor) && !isIgnored(constructor)) {
        testConstructor(constructor);
      }
    }
  }

        factories.add(factory);
      }
    }
    if (!Modifier.isAbstract(type.getRawType().getModifiers())) {
      for (Constructor<?> constructor : type.getRawType().getDeclaredConstructors()) {
        Invokable<T, T> invokable = type.constructor(constructor);
        if (!invokable.isPrivate() && !invokable.isSynthetic()) {
          factories.add(invokable);
        }
      }
    }

  }

  public void testPrivateClass() {
    NullPointerTester tester = new NullPointerTester();
    for (Constructor<?> constructor :
        PrivateClassWithPrivateConstructor.class.getDeclaredConstructors()) {
      tester.testConstructor(constructor);
    }
  }

  private interface Foo<T> {
    void doSomething(T bar, Integer baz);
  }

  private static class StringFoo implements Foo<String> {