add missing static handler list getters

src/main/java/me/youhavetrouble/preventstabby/api/event/PlayerEnterCombatEvent.java

@@ -45,4 +45,9 @@ public class PlayerEnterCombatEvent extends Event implements Cancellable {
     public HandlerList getHandlers() {
         return HANDLERS;
     }
+
+    @NotNull
+    public static HandlerList getHandlerList() {
+        return HANDLERS;
+    }
 }

src/main/java/me/youhavetrouble/preventstabby/api/event/PlayerLeaveCombatEvent.java

@@ -45,4 +45,9 @@ public class PlayerLeaveCombatEvent extends Event implements Cancellable {
     public HandlerList getHandlers() {
         return HANDLERS;
     }
+
+    @NotNull
+    public static HandlerList getHandlerList() {
+        return HANDLERS;
+    }
 }

src/main/java/me/youhavetrouble/preventstabby/api/event/PlayerTogglePvpEvent.java

@@ -59,4 +59,9 @@ public class PlayerTogglePvpEvent extends Event {
     public HandlerList getHandlers() {
         return HANDLERS;
     }
+
+    @NotNull
+    public static HandlerList getHandlerList() {
+        return HANDLERS;
+    }
 }