Multiple fixes/improvements

.gitignore

@@ -1,2 +1,3 @@
 .idea
+composer.lock
 vendor

composer.json

@@ -3,8 +3,8 @@
     "description": "Load guzzle service description from various file formats",
     "require": {
         "php": ">=5.5.0",
-        "symfony/config": "~3.0",
-        "symfony/yaml": "~3.0"
+        "symfony/config": "~3.0|^4.0",
+        "symfony/yaml": "~3.0|^4.0"
     },
     "license": "MIT",
     "authors": [

src/FileLoader.php

@@ -31,10 +31,9 @@ public function load($resource, $type = null)
             foreach($configValues["imports"] as $file) {
                 $configValues = array_merge_recursive($configValues, $this->import($this->locator->locate($file)));
             }
+            unset($configValues["imports"]);
         }
 
-        unset($configValues["imports"]);
-
         return $configValues;
     }
 

tests/fixtures/invalid.yml

@@ -1,2 +1,2 @@
-operations
-    certificates.add:
+operations:
+-certificates.add