[skip ci] adding action=DetectDefault in parser

ml-agents/mlagents/trainers/cli_utils.py

         type=str,
         nargs="*",
         help="Absolute paths of plugins to be loaded",
-        required=False
+        required=False,
+        action=DetectDefault
     )
     argparser.add_argument(
         "--env-args",

ml-agents/mlagents/trainers/settings.py

     no_graphics: bool = parser.get_default("no_graphics")
 
 
-@attr.s(auto_attribs=True)
-class PluginSettings:
-    plugins: Optional[List[str]] = parser.get_default("plugins")
-
+# @attr.s(auto_attribs=True)
+# class PluginSettings:
+#     plugins: Optional[List[str]] = parser.get_default("plugins")
+#
 
 @attr.s(auto_attribs=True)
 class RunOptions(ExportableSettings):
     engine_settings: EngineSettings = attr.ib(factory=EngineSettings)
     environment_parameters: Optional[Dict[str, EnvironmentParameterSettings]] = None
     checkpoint_settings: CheckpointSettings = attr.ib(factory=CheckpointSettings)
-    plugin_settings: PluginSettings = attr.ib(factory=PluginSettings)
+    # plugin_settings: PluginSettings = attr.ib(factory=PluginSettings)
+    plugins = parser.get_default("plugins")
-    cattr.register_structure_hook(PluginSettings, strict_to_cls)
+    # cattr.register_structure_hook(PluginSettings, strict_to_cls)
     cattr.register_structure_hook(EngineSettings, strict_to_cls)
     cattr.register_structure_hook(CheckpointSettings, strict_to_cls)
     cattr.register_structure_hook(

ml-agents/mlagents/trainers/initializer.py

+class Initializer:
+    def __init__(self):
+        pass
+
+    def load(self):
+        pass