Add constructor arguments to MissingAggregation.

src/Aggregation/MissingAggregation.php

@@ -20,6 +20,19 @@ class MissingAggregation extends AbstractAggregation
 {
     use BucketingTrait;
 
+    /**
+     * Inner aggregations container init.
+     *
+     * @param string $name
+     * @param string $field
+     */
+    public function __construct($name, $field = null)
+    {
+        parent::__construct($name);
+
+        $this->setField($field);
+    }
+
     /**
      * {@inheritdoc}
      */