Add non-deprecated adapter back with deprecations

Author: josevalim

lib/plug/adapters/cowboy.ex

@@ -0,0 +1,55 @@
+defmodule Plug.Adapters.Cowboy do
+  @moduledoc false
+
+  @doc false
+  @deprecated "Use Plug.Cowboy.http/3 instead"
+  def http(plug, opts, cowboy_options \\ []) do
+    unless using_plug_cowboy?(), do: warn_and_raise()
+    Plug.Cowboy.http(plug, opts, cowboy_options)
+  end
+
+  @doc false
+  @deprecated "Use Plug.Cowboy.https/3 instead"
+  def https(plug, opts, cowboy_options \\ []) do
+    unless using_plug_cowboy?(), do: warn_and_raise()
+    Plug.Cowboy.https(plug, opts, cowboy_options)
+  end
+
+  @doc false
+  @deprecated "Use Plug.Cowboy.shutdown/1 instead"
+  def shutdown(ref) do
+    unless using_plug_cowboy?(), do: warn_and_raise()
+    Plug.Cowboy.shutdown(ref)
+  end
+
+  @doc false
+  @deprecated "Use Plug.Cowboy.child_spec/4 instead"
+  def child_spec(scheme, plug, opts, cowboy_options \\ []) do
+    unless using_plug_cowboy?(), do: warn_and_raise()
+    Plug.Cowboy.child_spec(scheme, plug, opts, cowboy_options)
+  end
+
+  @doc false
+  @deprecated "Use Plug.Cowboy.child_spec/1 instead"
+  def child_spec(opts) do
+    unless using_plug_cowboy?(), do: warn_and_raise()
+    Plug.Cowboy.child_spec(opts)
+  end
+
+  defp using_plug_cowboy?() do
+    Code.ensure_loaded?(Plug.Cowboy)
+  end
+
+  defp warn_and_raise() do
+    error = """
+    please add the following dependency to your mix.exs:
+        {:plug_cowboy, "~> 1.0"}
+    This dependency is required by Plug.Adapters.Cowboy
+    which you may be using directly or indirectly.
+    Note you no longer need to depend on :cowboy directly.
+    """
+
+    IO.warn(error, [])
+    :erlang.raise(:exit, "plug_cowboy dependency missing", [])
+  end
+end