The implementation of method getConnection(username, password) completely discards the properties by passing a new empty properties object instead of using the one set externally by the connection pool (info).

We use Oracle UCP as our connection pool and we set connection properties like this:

PoolDataSource pds = oracle.ucp.jdbc.PoolDataSourceFactory.getPoolDataSource();
pds.setURL("jdbc:mariadb://127.0.0.1:3306/test");
pds.setUser("user");
pds.setPassword("pass");
pds.setConnectionFactoryClassName("org.mariadb.jdbc.MySQLDataSource");

Properties p = new Properties();
p.setProperty("properties", "useFractionalSeconds=true");
pds.setConnectionFactoryProperties(p);

Connection c = pds.getConnection();

Here the property 'useFractionalSeconds' is never set on the new connection since it's discarded by the datasource implementation...