title: How use thenEmpty and then thenReturn in Spring WebFlux?
body: <p>I'm new in Spring WebFlux and I have a problem. I want to return something like <code>Mono&lt;String&gt;</code> as follow:</p>
  
  <pre><code>@PostMapping("/test")
  public Mono&lt;String&gt; test(){
      return Mono.just("Test String")
             .thenEmpty(it -&gt; {
                  // Do something I need
                  System.out.println("Print somethings");
             })
             .thenReturn("Return String");
  }
  </code></pre>
  
  <p>I wish the method to return <code>Return String</code>, But it return nothing. What's the Problem?</p>