logback-android/src/main/java/ch/qos/logback/classic/boolex/OnErrorEvaluator.java
public boolean evaluate(ILoggingEvent event) throws NullPointerException,
      EvaluationException {
    return event.getLevel().levelInt >= Level.ERROR_INT;
  }
public boolean evaluate(ILoggingEvent event) throws NullPointerException,
      EvaluationException {
    return event.getLevel().levelInt >= Level.ERROR_INT;
  }
Return true if event passed as parameter has level ERROR or higher, returns
false otherwise.