title: Coupling FirebaseRecyclerViewAdapter to a Boolean/String Map.Entry
body: <p>I'm using the <code>FirebaseRecyclerViewAdapter</code> from the <code>com.firebaseui:firebase-ui:0.2.0</code> library in many locations of my app. My question is how to apply it in situations where the query argument returns a number of 'index' entry values (Map.Entry). </p>
  
  <p>As indicated in the Firebase documentation (<a href="https://www.firebase.com/docs/android/guide/structuring-data.html" rel="noreferrer">https://www.firebase.com/docs/android/guide/structuring-data.html</a>), I'm using indexes to keep the data structure flat. This leads to a situation in which I need to bind these indexes to my ViewHolder. Within the populate view method, I'm using the key of the index to retrieve the data to fill the viewholder with.</p>
  
  <p>I'm having trouble to create the adapter, not sure how to define 'modelClass' argument in case of a Boolean/String Map.Entry:</p>
  
  <pre><code>mAdapter = new FirebaseRecyclerViewAdapter&lt;Map.Entry&lt;String, Boolean&gt;, ItemViewHolder&gt;(???.class, R.layout.my_card, ItemViewHolder.class, getItemIndexQuery(mKey) ) {
  ...
  }
  </code></pre>