LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
// LoggerContext ctx = LoggerContext.getContext();
Configuration cfg = ctx.getConfiguration();
...
ctx.updateLoggers();

if (saveLog4j2Config == null) {
    System.clearProperty(ConfigurationFactory.CONFIGURATION_FILE_PROPERTY);
} else {
    System.setProperty(ConfigurationFactory.CONFIGURATION_FILE_PROPERTY, saveLog4j2Config);
    ((LoggerContext) LogManager.getContext(false)).reconfigure();
}