Adds an event listener to prevent the nether portal stargates from creating actual nether portals

src/main/java/net/knarcraft/stargate/listener/PortalEventListener.java

@@ -0,0 +1,24 @@
+package net.knarcraft.stargate.listener;
+
+import net.knarcraft.stargate.portal.PortalHandler;
+import org.bukkit.block.BlockState;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.world.PortalCreateEvent;
+
+public class PortalEventListener implements Listener {
+
+    @EventHandler
+    public void onPortalCreation(PortalCreateEvent event) {
+        if (event.isCancelled()) {
+            return;
+        }
+        for (BlockState block : event.getBlocks()) {
+            if (PortalHandler.getByBlock(block.getBlock()) != null) {
+                event.setCancelled(true);
+                return;
+            }
+        }
+    }
+
+}