@After
  public void tearDown() throws Exception {
    configuration.shutdown();

    writeSimpleConfigFile(configFile, Level.WARN);
    loggerContextRule.reconfigure();
  }
This config file is generated dynamically by the test class.
geode-log4j/src/integrationTest/java/org/apache/geode/logging/log4j/internal/impl/FastLoggerIntegrationTest.java