private void println(int logLevel, String msg, Throwable tr) {
        if (logLevel < logConfiguration.logLevel) {
            return;
        }
        printlnInternal(logLevel, ((msg == null || msg.length() == 0)
                ? "" : (msg + SystemCompat.lineSeparator))
                + logConfiguration.throwableFormatter.format(tr));
    }
Print a log in a new line.

@param logLevel the log level of the printing log
@param msg      the message you would like to log
@param tr       a throwable object to log
android/android_framework/base/src/main/java/com/elvishew/xlog/Logger.java