fix typespecs in UtilitySupervisor (#681)

* fix typespecs in UtilitySupervisor

* update changelog

CHANGELOG.md

@@ -4,6 +4,7 @@
  * Specify the order in which state fields will be printed in the error logs. [#614](https://github.com/membraneframework/membrane_core/pull/614)
  * Fix clock selection [#626](https://github.com/membraneframework/membrane_core/pull/626)
  * Log messages in the default handle_info implementation [#680](https://github.com/membraneframework/membrane_core/pull/680)
+ * Fix typespecs in Membrane.UtilitySupervisor [#681](https://github.com/membraneframework/membrane_core/pull/681)
 
 ## 1.0.0
  * Introduce `:remove_link` action in pipelines and bins.

lib/membrane/utility_supervisor.ex

@@ -25,16 +25,22 @@ defmodule Membrane.UtilitySupervisor do
 
   @doc """
   Starts a process under the utility supervisor.
+
+  Semantics of the `child_spec` argument is the same as in `Supervisor.child_spec/2`.
   """
-  @spec start_child(t, Supervisor.child_spec()) :: Supervisor.on_start_child()
+  @spec start_child(t, Supervisor.child_spec() | {module(), term()} | module()) ::
+          Supervisor.on_start_child()
   defdelegate start_child(supervisor, child_spec),
     to: Membrane.Core.SubprocessSupervisor,
     as: :start_utility
 
   @doc """
   Starts a process under the utility supervisor and links it to the current process.
+
+  Semantics of the `child_spec` argument is the same as in `Supervisor.child_spec/2`.
   """
-  @spec start_link_child(t, Supervisor.child_spec()) :: Supervisor.on_start_child()
+  @spec start_link_child(t, Supervisor.child_spec() | {module(), term()} | module()) ::
+          Supervisor.on_start_child()
   defdelegate start_link_child(supervisor, child_spec),
     to: Membrane.Core.SubprocessSupervisor,
     as: :start_link_utility