add support for images

src/Message/PayloadNotification.php

@@ -58,6 +58,12 @@ class PayloadNotification implements Arrayable
      */
     protected $tag;
 
+    /**
+     * @internal
+     *
+     * @var null|string
+     */
+    protected $image;
     /**
      * @internal
      *
@@ -114,6 +120,7 @@ public function __construct(PayloadNotificationBuilder $builder)
         $this->sound = $builder->getSound();
         $this->badge = $builder->getBadge();
         $this->tag = $builder->getTag();
+        $this->image = $builder->getImage();
         $this->color = $builder->getColor();
         $this->clickAction = $builder->getClickAction();
         $this->bodyLocationKey = $builder->getBodyLocationKey();
@@ -137,6 +144,7 @@ public function toArray()
             'sound' => $this->sound,
             'badge' => $this->badge,
             'tag' => $this->tag,
+            'image' => $this->image,
             'color' => $this->color,
             'click_action' => $this->clickAction,
             'body_loc_key' => $this->bodyLocationKey,

src/Message/PayloadNotificationBuilder.php

@@ -219,6 +219,22 @@ public function setTag($tag)
         return $this;
     }
 
+
+    /**
+     * Indicates the image that can be displayed in the notification
+     * Supports an url or internal image.
+     *
+     * @param string $image
+     *
+     * @return PayloadNotificationBuilder current instance of the builder
+     */
+    public function setImage($image)
+    {
+        $this->image = $image;
+
+        return $this;
+    }
+
     /**
      * Supported Android.
      *
@@ -375,6 +391,16 @@ public function getTag()
         return $this->tag;
     }
 
+    /**
+     * Get image.
+     *
+     * @return null|string
+     */
+    public function getImage()
+    {
+        return $this->image;
+    }
+
     /**
      * Get Color.
      *