code: private Connection createRealConnection(final long timeoutMillis) throws SQLException {
  
        if(timeoutMillis < 1L) {
  
           String usePassword = getPassword();
  
           Connection conn = dbConnection.datasource == null ?
                   DriverManager.getConnection(dbConnection.connectionString, dbConnection.user, usePassword) :
                   dbConnection.datasource.getConnection(dbConnection.user, usePassword);
           if(conn != null) {
              return conn;
           } else {
              throw new SQLException("Unable to create connection: driver/datasource returned [null]");
           }
  
        } else {
  
           try {
              return connectionTimeLimiter.callWithTimeout(() -> createRealConnection(0L), timeoutMillis, TimeUnit.MILLISECONDS);
           } catch(UncheckedTimeoutException ute) {
              throw new SQLException("Unable to create connection after waiting " + timeoutMillis + " ms");
           } catch(Exception e) {
              throw new SQLException("Unable to create connection: driver/datasource", e);
           }
        }
     }
docs: Creates a real database connection, failing if one is not obtained in the specified time.
  @param timeoutMillis The timeout in milliseconds.
  @return The connection.
  @throws SQLException on connection problem or timeout waiting for connection.