- added required inheritance method in MockDB to prevent compile error

ethereumj-core/src/test/java/org/ethereum/trie/MockDB.java

@@ -1,6 +1,9 @@
 package org.ethereum.trie;
 
 import java.io.IOException;
+import java.util.Map.Entry;
+import java.util.Spliterator;
+import java.util.function.Consumer;
 
 import org.iq80.leveldb.DB;
 import org.iq80.leveldb.DBException;
@@ -129,4 +132,16 @@ public class MockDB implements DB {
 		return addedItems;
 	}
 
+	@Override
+	public void forEach(Consumer<? super Entry<byte[], byte[]>> action) {
+		// TODO Auto-generated method stub
+		
+	}
+
+	@Override
+	public Spliterator<Entry<byte[], byte[]>> spliterator() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+	
 }