add ClientBuilder->setConnectionParams() (#507)

src/Elasticsearch/ClientBuilder.php

@@ -71,6 +71,9 @@ class ClientBuilder
     /** @var array */
     private $hosts;
 
+    /** @var array */
+    private $connectionParams;
+
     /** @var  int */
     private $retries;
 
@@ -312,6 +315,17 @@ public function setHosts($hosts)
         return $this;
     }
 
+    /**
+     * @param array $params
+     * @return $this
+     */
+    public function setConnectionParams(array $params)
+    {
+        $this->connectionParams = $params;
+
+        return $this;
+    }
+
     /**
      * @param int $retries
      * @return $this
@@ -425,8 +439,10 @@ public function build()
         }
 
         if (is_null($this->connectionFactory)) {
-            $connectionParams = [];
-            $this->connectionFactory = new ConnectionFactory($this->handler, $connectionParams, $this->serializer, $this->logger, $this->tracer);
+            if (is_null($this->connectionParams)) {
+                $this->connectionParams = [];
+            }
+            $this->connectionFactory = new ConnectionFactory($this->handler, $this->connectionParams, $this->serializer, $this->logger, $this->tracer);
         }
 
         if (is_null($this->hosts)) {