To make configuration backwards compatible, I think lager_event stays as a special sink, with other sinks able to be added

src/lager.app.src

@@ -43,8 +43,8 @@
             %% Number of rotated crash logs to keep, 0 means keep only the
             %% current one - default is 0
             {crash_log_count, 5},
-            %% Whether to redirect error_logger messages into lager - defaults to true
-            {error_logger_redirect, lager_event}, %% <-- sink name
+            %% Whether to redirect error_logger messages into the default lager_event sink - defaults to true
+            {error_logger_redirect, true},
             %% How many messages per second to allow from error_logger before we start dropping them
             {error_logger_hwm, 50},
             %% How big the gen_event mailbox can get before it is switched into sync mode
@@ -52,8 +52,8 @@
             %% Switch back to async mode, when gen_event mailbox size decrease from `async_threshold'
             %% to async_threshold - async_threshold_window
             {async_threshold_window, 5}, %% <-- per sink
-            {sinks, [
-                     {lager_event, [{async_threshold, 20}, {async_threshold_window, 5}]}
+            {extra_sinks, [
+                     {security, []}, %% Security sink has no async behavior
             ]},
         ]}
  ]}.