logback-android/src/main/java/ch/qos/logback/classic/util/ContextInitializer.java
private URL findConfigFileFromSystemProperties(boolean updateStatus) {
    String logbackConfigFile = OptionHelper.getSystemProperty(CONFIG_FILE_PROPERTY);
    if (logbackConfigFile != null) {
      URL result = null;
      try {
        File file = new File(logbackConfigFile);
        if (file.exists() && file.isFile()) {
          if (updateStatus) {
            statusOnResourceSearch(logbackConfigFile, this.classLoader, logbackConfigFile);
          }
          result = file.toURI().toURL();
        } else {
          result = new URL(logbackConfigFile);
        }
        return result;
      } catch (MalformedURLException e) {
        // so, resource is not a URL:
        // attempt to get the resource from the class path
        result = Loader.getResource(logbackConfigFile, this.classLoader);
        if (result != null) {
          return result;
        }
      } finally {
        if (updateStatus) {
          statusOnResourceSearch(logbackConfigFile, this.classLoader, result != null ? result.toString() : null);
        }
      }
    }
    return null;
  }
private URL findConfigFileFromSystemProperties(boolean updateStatus) {
    String logbackConfigFile = OptionHelper.getSystemProperty(CONFIG_FILE_PROPERTY);
    if (logbackConfigFile != null) {
      URL result = null;
      try {
        File file = new File(logbackConfigFile);
        if (file.exists() && file.isFile()) {
          if (updateStatus) {
            statusOnResourceSearch(logbackConfigFile, this.classLoader, logbackConfigFile);
          }
          result = file.toURI().toURL();
        } else {
          result = new URL(logbackConfigFile);
        }
        return result;
      } catch (MalformedURLException e) {
        // so, resource is not a URL:
        // attempt to get the resource from the class path
        result = Loader.getResource(logbackConfigFile, this.classLoader);
        if (result != null) {
          return result;
        }
      } finally {
        if (updateStatus) {
          statusOnResourceSearch(logbackConfigFile, this.classLoader, result != null ? result.toString() : null);
        }
      }
    }
    return null;
  }
Finds a configuration file by system property
@return the file; or {@code null} if not found