title: Reactor changes in Spring Boot 2 M4
body: <p>I have updated from Spring Boot 2.0.0.M3 to 2.0.0.M4, which updates Reactor from 3.1.0.M3 to 3.1.0.RC1. This causes my code to break in a number of places.
  <code>Mono.and()</code> now returns <code>Mono&lt;Void&gt;</code>, where previously it returned <code>Mono&lt;Tuple&gt;</code>
  This is also the case for <code>Mono.when()</code>
  The following code compiles with the older versions, but not with the new version</p>
  
  <pre><code>    Mono&lt;String&gt; m1 = Mono.just("A");
      Mono&lt;String&gt; m2 = Mono.just("B");
  
      Mono&lt;String&gt; andResult = m1.and(m2).map(t -&gt; t.getT1() + t.getT2());
      Mono&lt;String&gt; whenResult = Mono.when(m1, m2).map(t -&gt; t.getT1() + t.getT2());
  </code></pre>
  
  <p>Has there been any changes to how this should work?</p>