Implement Cancellable in ClaimModifiedEvent (#942)

- If canceled, GP stops processing the resize command (no error printed or potential overlapping claim displayed)

src/main/java/me/ryanhamshire/GriefPrevention/events/ClaimModifiedEvent.java

@@ -3,6 +3,7 @@ package me.ryanhamshire.GriefPrevention.events;
 
 import me.ryanhamshire.GriefPrevention.Claim;
 import org.bukkit.command.CommandSender;
+import org.bukkit.event.Cancellable;
 import org.bukkit.event.Event;
 import org.bukkit.event.HandlerList;
 
@@ -11,7 +12,7 @@ import org.bukkit.event.HandlerList;
  * a claim has changed. The CommandSender can be null in the event that the modification is called by the plugin itself.
  * Created by Narimm on 5/08/2018.
  */
-public class ClaimModifiedEvent extends Event
+public class ClaimModifiedEvent extends Event implements Cancellable
 {
 
     private static final HandlerList handlers = new HandlerList();
@@ -21,12 +22,15 @@ public class ClaimModifiedEvent extends Event
         return handlers;
     }
 
-    private final Claim claim;
+    private final Claim from;
+    private final Claim to;
     private CommandSender modifier;
+    private boolean cancelled;
 
-    public ClaimModifiedEvent(Claim claim, CommandSender modifier)
+    public ClaimModifiedEvent(Claim from, Claim to, CommandSender modifier)
     {
-        this.claim = claim;
+        this.from = from;
+        this.to = to;
         this.modifier = modifier;
     }
 
@@ -40,10 +44,22 @@ public class ClaimModifiedEvent extends Event
      * The claim
      *
      * @return the claim
+     * @deprecated Use the {@link #getTo() getTo} method.
      */
+    @Deprecated
     public Claim getClaim()
     {
-        return claim;
+        return to;
+    }
+
+    public Claim getFrom()
+    {
+        return from;
+    }
+
+    public Claim getTo()
+    {
+        return to;
     }
 
     /**
@@ -55,4 +71,16 @@ public class ClaimModifiedEvent extends Event
     {
         return modifier;
     }
+
+    @Override
+    public boolean isCancelled()
+    {
+        return cancelled;
+    }
+
+    @Override
+    public void setCancelled(boolean cancelled)
+    {
+        this.cancelled = cancelled;
+    }
 }