Added Block.getPistonMoveReaction, BlockPistonExtend and BlockPistonRetractEvent

By: Erik Broes <erikbroes@grum.nl>

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

@@ -0,0 +1,30 @@
+package org.bukkit.block;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public enum PistonMoveReaction {
+    MOVE(0),
+    BREAK(1),
+    BLOCK(2);
+
+    private int id;
+    private static Map<Integer, PistonMoveReaction> byId = new HashMap<Integer, PistonMoveReaction>();
+    static {
+        for (PistonMoveReaction reaction: PistonMoveReaction.values()) {
+            byId.put(reaction.id, reaction);
+        }
+    }
+
+    private PistonMoveReaction(int id) {
+        this.id = id;
+    }
+
+    public int getId() {
+        return this.id;
+    }
+
+    public static PistonMoveReaction getById(int id) {
+        return byId.get(id);
+    }
+}