How to mask values while writing log based on regexp pattern in fabric mode ?

Issue

• User has a class which extended the pattenlayout.
• User using this class to mask some of the values during print. User created this project as an fragment bundle and also modified the startup.properties to load the class before the pax-logging-api-1.7.2.jar and for the log4j.appender.framework.layout property user loading his class.
• Its not working. Need help on the same.
• In previous project user used slf4j where there is a method patten Encoding which help to do the same.
• How ever in fuse its not working. So user tried the above work around.