java1.6 allows covariant return type for overriding methods, use it for clone()

h2/src/main/org/h2/engine/ConnectionInfo.java

@@ -112,7 +112,7 @@ public class ConnectionInfo implements Cloneable {
         return KNOWN_SETTINGS.contains(s);
     }
 
-    public Object clone() throws CloneNotSupportedException {
+    public ConnectionInfo clone() throws CloneNotSupportedException {
         ConnectionInfo clone = (ConnectionInfo) super.clone();
         clone.prop = (Properties) prop.clone();
         clone.filePasswordHash = Utils.cloneByteArray(filePasswordHash);

h2/src/main/org/h2/engine/Engine.java

@@ -130,7 +130,7 @@ public class Engine implements SessionFactory {
                 // In serialized mode, database instance sharing is not possible
                 ci.setProperty("OPEN_NEW", "TRUE");
                 try {
-                    backup = (ConnectionInfo) ci.clone();
+                    backup = ci.clone();
                 } catch (CloneNotSupportedException e) {
                     throw DbException.convert(e);
                 }

h2/src/main/org/h2/engine/SessionRemote.java

@@ -294,8 +294,8 @@ public class SessionRemote extends SessionWithState implements DataHandler {
         ConnectionInfo backup = null;
         try {
             if (autoServerMode) {
-                backup = (ConnectionInfo) ci.clone();
-                connectionInfo = (ConnectionInfo) ci.clone();
+                backup = ci.clone();
+                connectionInfo = ci.clone();
             }
             if (openNew) {
                 ci.setProperty("OPEN_NEW", "true");