* Asserts that the collection under test contains exactly the given elements, respecting
   * cardinality but not order. Subclasses may override this method to provide stronger assertions,
   * e.g., to check ordering in lists, but realize that <strong>unless a test extends {@link
   * com.google.common.collect.testing.testers.AbstractListTester AbstractListTester}, a call to
   * {@code expectContents()} invokes this version</strong>.
   *