discard potential charset in content-type header
Elixir.UndefinedFunctionError: function nil.schema/0 is undefined or private
?, in nil.schema/0 File "lib/open_api_spex/operation.ex", line 170, in OpenApiSpex.Operation.cast_request_body/4 File "lib/open_api_spex/operation.ex", line 129, in OpenApiSpex.Operation.cast/4 File "lib/open_api_spex/plug/cast.ex", line 33, in OpenApiSpex.Plug.Cast.call/2