Using MySQLDataSource or MariaDbDataSource to connect from pool has a regression :

MariaDbDataSource datasource = new MariaDbDataSource();
datasource.setUser("USER");
datasource.setPassword("PWD");
datasource.setUrl("jdbc:mariadb://localhost:3306/db");

Connection will use current current windows user (if using windows), not user "USER1"

MariaDbDataSource datasource = new MariaDbDataSource();
datasource.setUser("USER");
datasource.setPassword("PWD");
datasource.setUrl("jdbc:mariadb://localhost:3306/db?user=USER1");

Connection will use user "USER1"

recommended way to connect a pool is using Driver implementation, not DataSource
example :
final HikariDataSource ds = new HikariDataSource();
ds.setMaximumPoolSize(20);
ds.setDriverClassName("org.mariadb.jdbc.Driver");
ds.setJdbcUrl("jdbc:mariadb://localhost:3306/db");
ds.addDataSourceProperty("user", "root");
ds.addDataSourceProperty("password", "myPassword");
ds.setAutoCommit(false);