Add missing PistonMoveReactions.

By: Senmori <thesenmori@gmail.com>

paper-api/src/main/java/org/bukkit/block/PistonMoveReaction.java

@@ -3,6 +3,10 @@ package org.bukkit.block;
 import java.util.HashMap;
 import java.util.Map;
 
+/**
+ * Represents how a block or entity will react when interacting with a piston
+ * when it is extending or retracting.
+ */
 public enum PistonMoveReaction {
 
     /**
@@ -16,7 +20,18 @@ public enum PistonMoveReaction {
     /**
      * Indicates that the block will resist being pushed or pulled.
      */
-    BLOCK(2);
+    BLOCK(2),
+    /**
+     * Indicates that the entity will ignore any interaction(s) with
+     * pistons.
+     * <br>
+     * Blocks should use {@link PistonMoveReaction#BLOCK}.
+     */
+    IGNORE(3),
+    /**
+     * Indicates that the block can only be pushed by pistons, not pulled.
+     */
+    PUSH_ONLY(4);
 
     private int id;
     private static Map<Integer, PistonMoveReaction> byId = new HashMap<Integer, PistonMoveReaction>();