expected.add(null);
    expectContents(expected);
  }

  /**
   * Returns the {@link Method} instance for {@link #testAdd_supportedNullPresent()} so that tests
   * can suppress it. See {@link CollectionAddTester#getAddNullSupportedMethod()} for details.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static Method getAddSupportedNullPresentMethod() {

import static com.google.common.collect.testing.testers.CollectionAddAllTester.getAddAllUnsupportedSomePresentMethod;
import static com.google.common.collect.testing.testers.CollectionAddTester.getAddUnsupportedNotPresentMethod;
import static com.google.common.collect.testing.testers.CollectionCreationTester.getCreateWithNullUnsupportedMethod;