title: FirebaseRecyclerAdapter not display my items in android version 3.2.1
body: <p>I am using FirebaseRecyclerAdapter to load and display items in RecyclerView. When I execute my code it is not displaying any item. Help would be much appreciated.</p>
  
  <p><strong>This is my Category Class:</strong> </p>
  
  <pre><code>public class Category {
  
  private String Name;
  private String Image;
  
  public Category()
  {
  
  }
  
  public Category(String name, String image)
  {
      Name = name;
      Image = image;
  }
  
  public String getName()
  {
      return Name;
  }
  
  public void setName(String name)
  {
      Name = name;
  }
  
  public String getImage()
  {
      return Image;
  }
  </code></pre>
  
  <p><strong>This is MenuViewHolder Class:</strong></p>
  
  <pre><code>public class MenuViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
  
  public TextView txtMenuName;
  public ImageView imageView;
  
  private ItemClickListener itemClickListener;
  
  public MenuViewHolder(@NonNull View itemView) {
      super(itemView);
  
      txtMenuName = (TextView)itemView.findViewById(R.id.menu_name);
      imageView = (ImageView)itemView.findViewById(R.id.menu_image);
  
      itemView.setOnClickListener(this);
  }
  
  public void setItemClickListener(ItemClickListener itemClickListener) {
      this.itemClickListener = itemClickListener;
  }
  
  @Override
  public void onClick(View v) {
   itemClickListener.onClick(v, getAdapterPosition(),false);
  }
  </code></pre>
  
  <p><strong>This is Home Class :</strong></p>
  
  <pre><code>  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_home);
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
      toolbar.setTitle("Menu");
      setSupportActionBar(toolbar);
  
  
      //Init Firebase
      database = FirebaseDatabase.getInstance();
      category = database.getReference("Category");
  
      FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
      fab.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
              Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                      .setAction("Action", null).show();
          }
      });
  
      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
      ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
              this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
      drawer.addDrawerListener(toggle);
      toggle.syncState();
  
      NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
      navigationView.setNavigationItemSelectedListener(this);
  
      //Set Name for user
      View headerView = navigationView.getHeaderView(0);
      txtFullName = (TextView)headerView.findViewById(R.id.txtFullName);
      txtFullName.setText(Common.currentUser.getName());
  
      //Load menu
      recycler_menu = (RecyclerView)findViewById(R.id.recycler_menu);
      recycler_menu.setHasFixedSize(true);
      layoutManager = new LinearLayoutManager(this);
      recycler_menu.setLayoutManager(layoutManager);
  
  
      options = new FirebaseRecyclerOptions.Builder&lt;Category&gt;()
              .setQuery(category, Category.class).build();
      loadMenu();
  
  }
  
  private void loadMenu() { FirebaseRecyclerAdapter&lt;Category,MenuViewHolder&gt; adapter = new FirebaseRecyclerAdapter&lt;Category, MenuViewHolder&gt;(options) {
  
  @NonNull
  @Override
  public MenuViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
      return null;
  }
  
  @Override
  protected void onBindViewHolder(@NonNull MenuViewHolder holder, int position, @NonNull Category model) {
     holder.txtMenuName.setText(model.getName());
      Picasso.with(getBaseContext()).load(model.getImage())
              .into(holder.imageView);
      final Category clickItem = model;
      holder.setItemClickListener(new ItemClickListener() {
          @Override
          public void onClick(View view, int position, boolean isLongClick) {
              Toast.makeText(Home.this,""+clickItem.getName(),Toast.LENGTH_SHORT).show();
          }
      });
  }};     recycler_menu.setAdapter(adapter);}
  </code></pre>
  
  <p><strong>here is my XML Layout content_home:</strong></p>
  
  <pre><code>&lt;android.support.v7.widget.RecyclerView
      android:id="@+id/recycler_menu"
      android:scrollbars="vertical"
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
  
  &lt;/android.support.v7.widget.RecyclerView&gt;
  </code></pre>
  
  <p></p>
  
  <p><strong>And this is menu_item Card view :</strong></p>
  
  <pre><code> &lt;RelativeLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
  
      &lt;ImageView
          android:id="@+id/menu_image"
          android:src="@drawable/food"
          android:scaleType="centerCrop"
          android:layout_width="match_parent"
          android:layout_height="match_parent" /&gt;
  
      &lt;TextView
          android:id="@+id/menu_name"
          android:text="Name of Menu"
          android:textColor="@android:color/white"
          android:background="#4f0e0d0e"
          android:textSize="20dp"
          android:gravity="center"
          android:layout_alignParentBottom="true"
          android:layout_width="match_parent"
          android:layout_height="wrap_content" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p></p>
  
  <p>This is the structure of my database:
  <a href="https://i.stack.imgur.com/vkL0K.png" rel="nofollow noreferrer">DataBase Structure</a></p>