Post upgrade to 12.0, workflow expressions with Log4j code failed to execute in Windchill PDMLink 12.0

• After upgrade to 12.0, no tasks getting generated on change activity workflow process.
• Expression with customization code of Log4j reports error

wt.util.WTException: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
Nested exception is: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
Nested exception is: wt.util.WTException: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
Nested exception is: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
wt.workflow.engine.FailedExpressionException: wt.util.WTException: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
Nested exception is: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
Nested exception is: wt.util.WTException: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
Nested exception is: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
at ext.utils.log.Log4jLogFactory.createLogger(Log4jLogFactory.java:29)
at ext.utils.log.LogFactory.newLogger(LogFactory.java:36)
at ext.arcam.change.ChangeUtils.<clinit>(ChangeUtils.java:48)
at wt.workflow.expr.WfExpression604192514.executemethod_1(WfExpression604192514.java:44)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at wt.workflow.definer.WfExpression.invokeByReflection(WfExpression.java:1464)
at wt.workflow.definer.WfExpression.executeTransition(WfExpression.java:1407)
at wt.workflow.definer.WfExpression.execute(WfExpression.java:523)
at wt.workflow.robots.WfExpressionRobot.run(WfExpressionRobot.java:162)
at wt.workflow.engine.StandardWfEngineService.runRobot(StandardWfEngineService.java:1184)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessor