title: Assertj Comparing extracted which are String arrays
body: <p>In my case I need to request the set of names from two different systems and verify they are equal (regardless order). Most probably I don't understand smth, but this code works fine:</p>
  
  <pre><code>assertThat(asList(assertThat(firstJSON)
      .flatExtracting("innerObject")
      .extracting("name")).stream().map(Object::toString).collect(Collectors.toList()))
      .containsExactlyElementsOf(
              asList(assertThat(secondJSON)
                      .flatExtracting("innerObject")
                      .extracting("name")).stream().map(Object::toString).collect(Collectors.toList()));
  </code></pre>
  
  <p>, but it looks really ugly and I want something like this:</p>
  
  <pre><code>assertThat(firstJSON)
      .flatExtracting("innerObject")
      .extracting("name")
      .containsExactlyElementsOf(
              assertThat(secondJSON)
                      .flatExtracting("innerObject")
                      .extracting("name"));
  </code></pre>
  
  <p>I've tried many functions like <code>isSubsetOf()</code> or <code>containsOnly()</code>, also I tried putting casting here and there but always catching some exception/error.</p>
  
  <p>How do I compare them?</p>