Move applications to extra_applications, and logger there

mix.exs

@@ -43,11 +43,38 @@ defmodule Ejabberd.MixProject do
 
   def application do
     [mod: {:ejabberd_app, []},
-     applications: [:idna, :inets, :kernel, :sasl, :ssl, :stdlib, :mix,
+
+      # https://hexdocs.pm/mix/1.17.2/Mix.Tasks.Compile.App.html
+      #
+      # both :extra_applications and :applications was found in your mix.exs.
+      # You most likely want to remove the :applications key,
+      # as all applications are derived from your dependencies
+      #
+      # :applications -
+      #  all applications your application depends on at runtime.
+      #  By default, this list is automatically inferred from your dependencies.
+      #  Mix and other tools use the application list in order to start
+      #  your dependencies before starting the application itself.
+      #
+      # :extra_applications -
+      #  a list of OTP applications your application depends on which are not included in :deps
+      #  (usually defined in deps/0 in your mix.exs). For example, here you can declare a dependency
+      #  on applications that ship with Erlang/OTP or Elixir, like :crypto or :logger.
+      #  Optional extra applications can be declared as a tuple, such as {:ex_unit, :optional}.
+      #  Mix guarantees all non-optional applications are started before your application starts.
+      #
+      # :included_applications -
+      #  specifies a list of applications that will be included in the application.
+      #  It is the responsibility of the primary application to start the supervision tree
+      #  of all included applications, as only the primary application will be started.
+      #  A process in an included application considers itself belonging to the primary application.
+      #
+
+     extra_applications: [:idna, :inets, :kernel, :logger, :sasl, :ssl, :stdlib, :mix,
                     :fast_tls, :fast_xml, :fast_yaml, :jose,
                     :p1_utils, :stringprep, :syntax_tools, :yconf, :xmpp]
      ++ cond_apps(),
-     included_applications: [:mnesia, :os_mon, :logger,
+     included_applications: [:mnesia, :os_mon,
                              :cache_tab, :eimp, :mqtree, :p1_acme,
                              :p1_oauth2, :pkix]
      ++ cond_included_apps()]