Remove field parameter from AbstractAggregation.

src/Aggregation/AbstractAggregation.php

@@ -60,14 +60,11 @@ abstract class AbstractAggregation implements NamedBuilderInterface
      * Inner aggregations container init.
      *
      * @param string $name
-     * @param string $field
      */
-    public function __construct($name, $field = null)
+    public function __construct($name)
     {
         $this->name = $name;
-        if ($field !== null) {
-            $this->setField($field);
-        }
+
         $this->aggregations = new NamedBuilderBag();
     }