I continued playing around with the scenario, looks like the problem is not necessarily a node action, but when actions are called when deeper jbpm nodes are traversed.

 <start-state name="start">
        <transition to="startNode"/>
    </start-state>
    
    <node name="startNode">
          <action expression="#{loanProcessing.startNodeAction}"></action>     
          <transition name="next" to="secondNode"></transition>
     </node>
     
     <node name="secondNode">
          <action expression="#{loanProcessing.secondNodeAction}"></action>     
          <transition name="next" to="initialContact"></transition>
     </node>

For the snippet above, bijection works when loanProcessing.startNodeAction gets called but does not happen when loanProcessing.secondNodeAction is invoked.

Did some more digging on this, even Decision nodes has this problem. During debug, I noticed that seam(through SeamELResolver, Namespace and Context) is pulling out the component(loanProcessing) from the method context. This caused the BijectionInterceptor not to be invoked, hence the loanId was not set.

The relevant interceptor chain is as follows:
...MethodContextInterceptor -- BusinessProcessInterceptor -- ConversationInterceptor -- BijectionInterceptor...

Is there any solution/fix to this, Or any workarounds? I understand that splitting the action component to multiple classes may sort of work, but I'd prefer to keep things in the same class.

Any insight on this is appreciated.

I just wanted to share what I have done to work around this problem.

I created an interceptor that sits between MethodContextInterceptor and BusinessProcessInterceptor to remove the component from the MethodContext. This interceptor is only activated on jBpmHandlers, by means of an annotation.

The relevant codes are

Interceptor

@SuppressWarnings("serial")
@Interceptor(stateless = true, within = MethodContextInterceptor.class,

public class JbpmHandlerInterceptor extends AbstractInterceptor{
     @AroundInvoke
     public Object aroundInvoke(InvocationContext ctx) throws Exception {          
          Component comp = getComponent();
          if (comp!=null){
               String name = comp.getName();
               Contexts.getMethodContext().set(name,null);
          }
          Object ret = ctx.proceed();          
          return ret;
     }
}

Annotation

@Target(TYPE)
@Retention(RUNTIME)
@Interceptors(JbpmHandlerInterceptor.class)
public @interface JbpmHandler {
}

jBpm Handler class

@Name("loanProcessing")
@JbpmHandler
public class LoanProcessingAction {
...
}

It worked in my test scenario so far, but since I have no deep knowledge of the framework, I cant tell if there's a scenario that this will break. Do you foresee any problems related to this approach?

Just reformatting my previous post.

@SuppressWarnings("serial")
@Interceptor(stateless = true, within = MethodContextInterceptor.class,

public class JbpmHandlerInterceptor extends AbstractInterceptor{
     @AroundInvoke
     public Object aroundInvoke(InvocationContext ctx) throws Exception {          
          Component comp = getComponent();
          if (comp!=null){
               String name = comp.getName();
               Contexts.getMethodContext().set(name,null);
          }
          Object ret = ctx.proceed();          
          return ret;
     }
}

@Target(TYPE)
@Retention(RUNTIME)
@Interceptors(JbpmHandlerInterceptor.class)
public @interface JbpmHandler {
}

@Name("loanProcessing")
@JbpmHandler
public class LoanProcessingAction {
...
}