Allowed empty db password

TASMAN-core/src/main/java/it/inaf/ia2/tsm/datalayer/DataSourceWrapper.java

@@ -65,7 +65,7 @@ public class DataSourceWrapper implements Serializable {
             ds.setDriverClassName(driverClassName);
             ds.setUrl(url);
             ds.setUsername(credentials.getUsername());
-            ds.setPassword(credentials.getPassword());
+            ds.setPassword(credentials.getPassword() != null ? credentials.getPassword() : "");
             ds.setInitialSize(5);
             ds.setMaxActive(10);
             ds.setMaxIdle(5);