Replaced array_walk with array_map

In Connection::getURI, array_walk was used together with passing the
values as references, to change the original array.
Passing values as references is error-prone and discouraged for quite
some time.
Also, when using in conjunction with PHP 8.0, it will fail.

array_map can do the same thing as the original array_walk
implementation, but without the downsides of having side effects and
having to pass values as references.

src/Elasticsearch/Connections/Connection.php

@@ -346,15 +346,17 @@ function ($response) use ($connection, $transport, $request, $options) {
     private function getURI(string $uri, ?array $params): string
     {
         if (isset($params) === true && !empty($params)) {
-            array_walk(
-                $params,
-                function (&$value, &$key) {
+            $params = array_map(
+                function ($value) {
                     if ($value === true) {
-                        $value = 'true';
+                        return 'true';
                     } elseif ($value === false) {
-                        $value = 'false';
+                        return 'false';
                     }
-                }
+
+                    return $value;
+                },
+                $params
             );
 
             $uri .= '?' . http_build_query($params);

tests/Elasticsearch/Tests/Connections/ConnectionTest.php

@@ -363,4 +363,36 @@ public function testHeaderClientParamIsResetAfterSent()
         $headersAfter = $connection->getHeaders();
         $this->assertEquals($headersBefore, $headersAfter);
     }
+
+        /**
+     * @depends testGetHeadersContainUserAgent
+     *
+     * @covers \Connection::performRequest
+     * @covers \Connection::getURI
+     */
+    public function testParametersAreSent()
+    {
+        $connectionParams = [];
+        $host = [
+            'host' => 'localhost'
+        ];
+        $requestParams = [
+            'foo' => true,
+            'baz' => false,
+            'bar' => 'baz'
+        ];
+
+        $connection = new Connection(
+            ClientBuilder::defaultHandler(),
+            $host,
+            $connectionParams,
+            $this->serializer,
+            $this->logger,
+            $this->trace
+        );
+        $result  = $connection->performRequest('GET', '/', $requestParams);
+        $request = $connection->getLastRequestInfo()['request'];
+
+        $this->assertEquals('/?foo=true&baz=false&bar=baz', $request['uri']);
+    }
 }