src/main/java/com/arpnetworking/logback/KeyValueEncoder.java
String createMessage(
            final ILoggingEvent event,
            @Nullable final String eventName,
            @Nullable final String[] keys,
            @Nullable final Object[] values) {

        final String formatString = buildFormatString(eventName, keys);
        final LoggingEventWrapper eventWrapper = new LoggingEventWrapper(event, formatString, values);
        return layout.doLayout(eventWrapper);
    }
String createMessage(
            final ILoggingEvent event,
            @Nullable final String eventName,
            @Nullable final String[] keys,
            @Nullable final Object[] values) {

        final String formatString = buildFormatString(eventName, keys);
        final LoggingEventWrapper eventWrapper = new LoggingEventWrapper(event, formatString, values);
        return layout.doLayout(eventWrapper);
    }
/* package private