private boolean isValidOrNull(PoolableConnection connection) {
        // connection nullable
        try {
            return connection == null || (connection.getExpires() > System.currentTimeMillis() && !connection.isClosed());
        } catch (SQLException sqle) {
            LOGGER_CONNECTION.error(sqle, "Error while checking if a connection is closed.");
            return false;
        }
    }
A fully concurrent implementation of a connection pool.

@author Per Minborg
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/internal/component/ConnectionPoolComponentImpl.java