fix(agent): do not call 'get' directly on Symfony requests (#1151)

Calling `get` on a request object is not best practice, and has been
deprecated. It is advised to instead call get on the proper member, in
our case, `attributes`.

closes #1148

Author: ZNeumann

agent/fw_symfony4.c

@@ -130,6 +130,9 @@ NR_PHP_WRAPPER_END
 NR_PHP_WRAPPER(nr_symfony4_name_the_wt) {
   zval* event = NULL;
   zval* request = NULL;
+  zval* request_attrs = NULL;
+  zval* route_rval = NULL;
+  zval* controller_rval = NULL;
 
   /* Warning avoidance */
   (void)wraprec;
@@ -173,9 +176,16 @@ NR_PHP_WRAPPER(nr_symfony4_name_the_wt) {
   request = nr_php_call(event, "getRequest");
   if (nr_php_object_instanceof_class(
           request, "Symfony\\Component\\HttpFoundation\\Request" TSRMLS_CC)) {
+    request_attrs = nr_php_get_zval_object_property(request, "attributes");
+    if (!nr_php_is_zval_valid_object(request_attrs)) {
+      nrl_verbosedebug(
+          NRL_TXN, "Symfony 4: Request->attributes could not be obtained");
+      goto end;
+    }
+
     /* Let's look for _route first. */
-    zval* route_rval
-        = nr_symfony_object_get_string(request, "_route" TSRMLS_CC);
+    route_rval
+        = nr_symfony_object_get_string(request_attrs, "_route" TSRMLS_CC);
 
     if (route_rval) {
       if (NR_SUCCESS
@@ -187,8 +197,8 @@ NR_PHP_WRAPPER(nr_symfony4_name_the_wt) {
       nr_php_zval_free(&route_rval);
     } else {
       /* No _route. Look for _controller. */
-      zval* controller_rval
-          = nr_symfony_object_get_string(request, "_controller" TSRMLS_CC);
+      controller_rval
+          = nr_symfony_object_get_string(request_attrs, "_controller" TSRMLS_CC);
 
       if (controller_rval) {
         if (NR_SUCCESS