title: Firebase Authentication Android fetchProvidersForEmail() bug?
body: <p>I'm trying to enable "Multiple accounts per email address", but I'm not really sure how it works. fetchProvidersForEmail() seems to return unexpected results.</p>
  
  <p>I have the following code.</p>
  
  <pre><code>firebaseAuth.fetchProvidersForEmail("email").addOnCompleteListener(new OnCompleteListener&lt;ProviderQueryResult&gt;() {
      @Override
      public void onComplete(@NonNull Task&lt;ProviderQueryResult&gt; task) {
          if (task.isSuccessful()) {
              List&lt;String&gt; providers = task.getResult().getProviders();
              if (providers != null) {
                  Timber.d(providers.toString());
              } else {
                  Timber.d("provider null");
              }
          } else {
              Timber.d("task fail");
          }
      }
  });
  </code></pre>
  
  <p><strong>Scenario 1</strong></p>
  
  <ol>
  <li>By default, sign in user with Google. <code>fetchProvidersForEmail()</code> returns <code>[google.com]</code>.</li>
  <li>Enable "Multiple accounts per email address". <code>fetchProvidersForEmail()</code> returns <code>[]</code>.</li>
  <li>Disable "Multiple accounts per email address". <code>fetchProvidersForEmail()</code> returns <code>[google.com]</code> again.</li>
  </ol>
  
  <p><strong>Scenario 2</strong></p>
  
  <ol>
  <li>Enable "Multiple accounts per email address". Sign in user with Email/Password first.</li>
  <li><code>fetchProvidersForEmail()</code> returns <code>[password]</code>.</li>
  <li>Sign in user with Google. <code>fetchProvidersForEmail()</code> still returns <code>[password]</code> only.</li>
  <li>Disable "Multiple accounts per email address". <code>fetchProvidersForEmail()</code> now returns <code>[google.com]</code> only.</li>
  </ol>
  
  <p><strong>Conclusion</strong></p>
  
  <ol>
  <li>When "Multiple accounts per email address" is not enabled, <code>[google.com]</code> is returned correctly. It is also given priority of Email/Password that was created when "Multiple accounts per email address" is enabled.</li>
  <li>When "Multiple accounts per email address" is enabled, <code>[password]</code> is returned correctly. <code>[google.com]</code> is never returned.</li>
  </ol>
  
  <p>Is this actually the correct behavior?</p>