title: How can I fall back the wrong element onErrorReturn of a project reactor flux?
body: <p>Lets say I have a flux where an element throws an error.</p>
  
  <pre><code> Flux.just("aeiou","aeio").map(x -&gt; {
             if(!x.endsWith("u")){throws Exception;}
             return x;})
        .onErrorReturn(/*This only accepts a new element*/)
        .map(x -&gt; x+";")
        .subscribe();
  
   Flux.just("aeiou","aeio").map(x -&gt; {
             if(!x.endsWith("u")){throws Exception;}
             return x;})
        .onErrorResume(/*This doesn't do the next steps*/)
        .map(x -&gt; x+";")
        .subscribe();
  </code></pre>
  
  <p>I want something like this</p>
  
  <pre><code> Flux.just("aeiou","aeio").map(x -&gt; {
             if(!x.endsWith("u")){throws Exception;}
             return x;})
        .onErrorReturn(x -&gt; x + "u")
        .map(x -&gt; x+";")
        .subscribe();
  </code></pre>
  
  <p>Documentation seems wrong
  <a href="http://projectreactor.io/docs/core/release/reference/#_fallback_method" rel="nofollow noreferrer">http://projectreactor.io/docs/core/release/reference/#_fallback_method</a></p>
  
  <pre><code>Flux.just("key1", "key2")
     .flatMap(k -&gt; callExternalService(k)) 
     .onErrorResume(e -&gt; getFromCache(k)); //k not resolved here
  </code></pre>