feat(olp): add default config

apps/emqx/etc/emqx.conf

@@ -833,6 +833,33 @@ force_shutdown {
   max_heap_size = 32MB
 }
 
+overload_protection {
+ ## React on system overload or not
+ ## @doc overload_protection.enable
+ ## ValueType: Boolean
+ ## Default: false
+ enable = false
+
+ ## Backoff delay in ms
+ ## @doc overload_protection.backoff_delay
+ ## ValueType: Integer
+ ## Range: (0, infinity)
+ ## Default: 1
+ backoff_delay = 1
+
+ ## Backoff GC enabled
+ ## @doc overload_protection.backoff_gc
+ ## ValueType: Boolean
+ ## Default: true
+ backoff_gc = true
+
+ ## Backoff hibernation enabled
+ ## @doc overload_protection.backoff_hibernation
+ ## ValueType: Boolean
+ ## Default: true
+ backoff_hibernation = true
+}
+
 force_gc {
   ## Force the MQTT connection process GC after this number of
   ## messages or bytes passed through.