[commands] Unwrap Parameter if given as default to commands.parameter

Author: Soheab

discord/ext/commands/parameters.py

@@ -247,6 +247,12 @@ async def wave(ctx, to: discord.User = commands.parameter(default=lambda ctx: ct
 
         .. versionadded:: 2.3
     """
+    if isinstance(default, Parameter):
+        if displayed_default is empty:
+            displayed_default = default._displayed_default
+
+        default = default._default
+
     return Parameter(
         name='empty',
         kind=inspect.Parameter.POSITIONAL_OR_KEYWORD,