title: RxJava observe multiple observers in single subscriber
body: <p><strong>Code</strong></p>
  
  <pre><code>Author author = baseRealm.where(Author.class).equalTo("id", mId).findFirst();
  
  public boolean checkGlobalSyncStatus(Author author, List&lt;Books&gt; mBooks) {
  
      final boolean[] isJobSynchronized = {false};
  
      Observable.fromIterable(mBooks)
              .filter(Books::isChanged)
              .doOnNext(book -&gt; isJobSynchronized[0] = true)
              .just(author)
              .flatMapIterable(Author::getAllBooks)
              .filter(MyBook::isChanged)
              .doOnNext(mBook -&gt; isJobSynchronized[0] = true)
              .just(author)
              .flatMapIterable(Author::getAllWriters)
              .filter(Writers::isChanged)
              .doOnNext(jobPage -&gt; isJobSynchronized[0] = true)
              .subscribe();
  
      return isJobSynchronized[0];
  }
  </code></pre>
  
  <p><strong>Problem</strong></p>
  
  <p><code>fromIterable(mBooks)</code> is called from <em>static-reference</em> <code>Observable</code> <strong>BUT</strong> <code>just(author)</code> is called from <em>instance-reference</em>. </p>
  
  <p>I only want to get this operation done in single query. I can make different observable for each and perform desired operation but that would be lengthy. </p>
  
  <p><strong>Why?</strong></p>
  
  <p>By doing so, <code>SonarQube</code> is giving me unsuccessful check and forcing me to remove <em>instance-reference</em>.</p>
  
  <p>Any alternatives will be appreciated. </p>
  
  <hr>
  
  <p><a href="https://i.stack.imgur.com/eeHAg.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eeHAg.jpg" alt="Lint analysis"></a></p>