Fix user for user instance.

manifests/config.pp

@@ -93,7 +93,7 @@ define mpd::config (
   String $pid_file                                            = "${mpd_home}/pid",
   String $playlist_directory                                  = "${music_directory}/playlists",
   String $state_file                                          = "${mpd_home}/state",
-  String $user                                                = 'mpd',
+  Optional[String] $user                                      = 'mpd',
   String $bind_to_address                                     = 'any',
   Integer $port                                               = 6600,
   Enum['default','secure','verbose'] $log_level               = 'default',

manifests/user_instance.pp

@@ -48,6 +48,7 @@ define mpd::user_instance (
 
   mpd::config { "MPD instance for ${user}":
     config_file => $config_file,
+    user        => undef,
     owner       => $user,
     group       => $group,
     *           => $conf_defaults + $mpd_conf,

metadata.json

@@ -36,6 +36,12 @@
 			]
 		}
 	],
+	"requirements": [
+		{
+			"name": "puppet",
+			"version_requirement": ">= 5.5.10 < 8.0.0"
+		}
+	],
 	"pdk-version": "2.5.0",
 	"template-url": "pdk-default#2.5.0",
 	"template-ref": "tags/2.5.0-0-g369d483"