Allow empty array in config for uaa->clients

Author: svkrieger

lib/cloud_controller/config_schemas/base/api_schema.rb

@@ -59,13 +59,13 @@ class ApiSchema < VCAP::Config
               :client_timeout => Integer,
               optional(:symmetric_secret) => String,
               optional(:symmetric_secret2) => String,
-              optional(:clients) => [
+              optional(:clients) => enum([
                 {
                   'name' => String,
                   'id' => String,
                   'secret' => String
                 }
-              ]
+              ], NilClass)
             },
 
             optional(:allow_user_creation_by_org_manager) => bool,