defined package level logger:
<logger name="com.company.app"
level="ALL" additivity="false">
<appender-ref ref="STDOUT-my"/>
</logger>

Get nested class logger:
ch.qos.logback.classic.Logger logger =
(ch.qos.logback.classic.Logger) LoggerFactory.getLogger(com.company.app.classes.TestClass.class);

By using getAppender() or iteratorForAppenders() I expect to get appenders even those which are not specified explicitly for the logger but inherited from ancestors:
Appender<ILoggingEvent> appender = logger.getAppender("STDOUT-my");
Gives "null"

This gives only appenders configured explicitly for the logger like:
<logger name="com.company.app.classes.TestClass"
level="ALL">
<appender-ref ref="STDOUT-my"/>
</logger>

Gives "ch.qos.logback.core.ConsoleAppender[STDOUT-my]"

The only problem description I've found is - http://logback.10977.n7.nabble.com/How-to-programmatically-find-an-appender-for-a-logger-td12010.html