Multimap<String, String> studentPhoneNumbers = HashMultimap.create(); studentPhoneNumbers.put("John", "1234567890"); studentPhoneNumbers.put("John", "9876543210"); studentPhoneNumbers.put("Alice", "5555555555"); Multimap<String, String> bookAuthors = HashMultimap.create(); bookAuthors.put("BookA", "AuthorA"); bookAuthors.put("BookA", "AuthorB"); bookAuthors.put("BookB", "AuthorC");