title: Firebase throws no setter/field for photo_url found in class models.Post$Photo
body: <p>Testing the new Google Firebase and i am getting this error when displaying data from the firebase realtime database. See error below.
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  <pre><code>06-09 22:23:05.335 28373-28373/appsng.com.pappaz V/BitmapFactory: DecodeImagePath(decodeResourceStream3) : res/mipmap-mdpi-v4/avatar.jpg
      06-09 22:23:05.375 28373-28373/appsng.com.pappaz V/BitmapFactory: DecodeImagePath(decodeResourceStream3) : res/mipmap-mdpi-v4/thumb_up.png
      06-09 22:23:05.380 28373-28373/appsng.com.pappaz V/BitmapFactory: DecodeImagePath(decodeResourceStream3) : res/mipmap-mdpi-v4/message.png
      06-09 22:23:05.390 28373-28373/appsng.com.pappaz W/ClassMapper: No setter/field for photo_url found on class models.Post$Photo
      06-09 22:23:05.390 28373-28373/appsng.com.pappaz W/ClassMapper: No setter/field for photo_url found on class models.Post$Photo
      06-09 22:23:05.390 28373-28373/appsng.com.pappaz W/ClassMapper: No setter/field for photo_url found on class models.Post$Photo
      06-09 22:23:05.390 28373-28373/appsng.com.pappaz W/ClassMapper: No setter/field for photo_url found on class models.Post$Photo
      06-09 22:23:05.395 28373-28373/appsng.com.pappaz V/BitmapFactory: DecodeImagePath(decodeResourceStream3) : res/mipmap-mdpi-v4/clear.png
      06-09 22:23:05.400 28373-28373/appsng.com.pappaz D/data: null
      06-09 22:23:05.400 28373-28373/appsng.com.pappaz V/BitmapFactory: DecodeImagePath(decodeResourceStream3) : res/mipmap-hdpi-v4/no_image_square.png
      06-09 22:23:05.415 28373-28373/appsng.com.pappaz D/data: null
      06-09 22:23:05.415 28373-28373/appsng.com.pappaz D/data: null
      06-09 22:23:05.420 28373-28373/appsng.com.pappaz D/data: null
      06-09 22:23:05.450 28373-28540/appsng.com.pappaz I/System.out: (HTTPLog)-Static: isSBSettingEnabled false
      06-09 22:23:05.450 28373-28540/appsng.com.pappaz I/System.out: (HTTPLog)-Static: isShipBuild true
      06-09 22:23:05.450 28373-28540/appsng.com.pappaz I/System.out: (HTTPLog)-Thread-12056-119902642: SmartBonding Enabling is false, SHIP_BUILD is true, log to file is false, DBG is false
      06-09 22:23:05.450 28373-28540/appsng.com.pappaz I/System.out: (HTTPLog)-Static: isSBSettingEnabled false
      06-09 22:23:05.465 28373-28373/appsng.com.pappaz W/ClassMapper: No setter/field for photo_url found on class models.Post$Photo
      06-09 22:23:05.470 28373-28540/appsng.com.pappaz I/System.out: KnoxVpnUidStorageknoxVpnSupported API value returned is false
      06-09 22:23:05.470 28373-28373/appsng.com.pappaz D/data: null
      06-09 22:23:05.590 28373-28373/appsng.com.pappaz I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@1cf1f8b7 time:10585179
      06-09 22:23:10.090 28373-28413/appsng.com.pappaz V/FA: Inactivity, disconnecting from AppMeasurementService
  </code></pre>
  
  <p><br/>
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  <p>And it seems to be coming from my model class. See my model Post class below</p>
  
  <pre><code>package models;
  
  import com.google.firebase.database.Exclude;
  import com.google.firebase.database.IgnoreExtraProperties;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Map;
  
  
  public class Post implements Serializable{
  
      public String id,user_id,user_name,content,created,likes,user_photo;
      ArrayList&lt;Photo&gt; photos = new ArrayList&lt;&gt;();
      ArrayList&lt;Comment&gt; comments = new ArrayList&lt;&gt;();
  
      public Post(){
  
      }
  
      public Post(String id,String user_id,String user_name,String content,String created,String likes,String user_photo){
          this.id = id;
          this.user_id = user_id;
          this.user_name = user_name;
          this.content = content;
          this.created = created;
          this.likes = likes;
          this.user_photo = user_photo;
      }
  
  
      @Exclude
      public Map&lt;String, Object&gt; toMap() {
          HashMap&lt;String, Object&gt; result = new HashMap&lt;&gt;();
          result.put("user_id", user_id);
          result.put("user_name", user_name);
          result.put("content", content);
          result.put("created", created);
          result.put("likes", likes);
          result.put("user_photo", user_photo);
  
          return result;
      }
  
  
      public ArrayList&lt;Comment&gt; getComments() {
          return comments;
      }
  
      public ArrayList&lt;Photo&gt; getPhotos() {
          return photos;
      }
      //// getters ////
  
      public String getId(){
          return this.id;
      }
  
      public String getUser_id(){
          return this.user_id;
      }
  
      public String getUser_name(){
          return this.user_name;
      }
  
      public String getUser_photo(){
          return this.user_photo;
      }
  
      public String getContent(){
          return this.content;
      }
  
      public String getCreated(){
          return this.created;
      }
  
      public String getLikes(){
          return this.likes;
      }
  
      //// setters ////
  
      public void setComments(ArrayList&lt;Comment&gt; value){
          this.comments = value;
      }
  
      public void setPhotos(ArrayList&lt;Photo&gt; value){
          this.photos = value;
      }
  
  
      public void setId(String value){
          this.id = value;
      }
  
      public void setUser_id(String value){
          this.user_id = value;
      }
  
      public void setUser_name(String value){
          this.user_name = value;
      }
  
      public void setUser_photo(String value){
          this.user_photo = value;
      }
  
      public void setContent(String value){
          this.content = value;
      }
  
      public void setCreated(String value){
          this.created = value;
      }
  
      public void setLikes(String value){
          this.likes = value;
      }
  
  
  
      public String toString(){
          return this.user_id;
      }
  
      public static class Photo implements Serializable{
  
          String photo_url;
  
          public Photo(){
  
          }
  
          public Photo(String photo_url){
              this.photo_url = photo_url;
          }
  
          public String getPhotoUrl(){
              return photo_url;
          }
  
          public void setPhotoUrl(String photo_url){
              this.photo_url = photo_url;
          }
  
          public String toString(){
              return this.photo_url;
          }
  
      }
  
  
  
  
      public static class Comment implements Serializable{
  
          public String id,user_id,user_name,user_photo,timestamp,content;
  
          public Comment(){
  
          }
  
          public Comment(String id,String user_id,String user_name,String user_photo,String timestamp,String content){
              this.id = id;
              this.user_id = user_id;
              this.user_name = user_name;
              this.user_photo = user_photo;
              this.timestamp = timestamp;
              this.content = content;
          }
  
          @Exclude
          public Map&lt;String, Object&gt; toMap() {
              HashMap&lt;String, Object&gt; result = new HashMap&lt;&gt;();
              result.put("id", id);
              result.put("user_id", user_id);
              result.put("user_name", user_name);
              result.put("user_photo", user_photo);
              result.put("timestamp", timestamp);
              result.put("content", content);
              return result;
          }
  
  
  
          //// getters ////
          public String getId(){
              return this.id;
          }
  
          public String getUser_id(){
              return this.user_id;
          }
  
          public String getUser_name(){
              return this.user_name;
          }
  
          public String getUser_photo(){
              return this.user_photo;
          }
  
          public String getTimestamp(){
              return this.timestamp;
          }
  
          public String getContent(){
              return this.content;
          }
  
          //// setters ////
  
          public void setId(String value){
              this.id = value;
          }
  
          public void setUser_id(String value){
              this.user_id = value;
          }
  
          public void setUser_name(String value){
              this.user_name = value;
          }
  
          public void setUser_photo(String value){
              this.user_photo = value;
          }
  
          public void setTimestamp(String value){
              this.timestamp = value;
          }
  
          public void setContent(String value){
              this.content = value;
          }
  
  
  
          public String toString(){
              return this.id;
          }
  
      }
  </code></pre>