Likely legacy muck from the LogbackLogManager that was never cleaned up:

```
  private String getLogConfigDir() {
    String logConfigDir = System.getProperty(KEY_LOG_CONFIG_DIR);

    if (Strings.isNullOrEmpty(logConfigDir)) {
      logConfigDir = applicationConfiguration.getConfigurationDirectory().getAbsolutePath();

      System.setProperty(KEY_LOG_CONFIG_DIR, logConfigDir);
    }

    return logConfigDir;
  }
```