SPIGOT-3664: Add Material getter to ChunkSnapshot

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/ChunkSnapshot.java

@@ -31,6 +31,16 @@ public interface ChunkSnapshot {
      */
     String getWorldName();
 
+    /**
+     * Get block type for block at corresponding coordinate in the chunk
+     *
+     * @param x 0-15
+     * @param y 0-127
+     * @param z 0-15
+     * @return block material type
+     */
+    Material getBlockType(int x, int y, int z);
+
     /**
      * Get block type for block at corresponding coordinate in the chunk
      *