WID 6.0.2 custom mediaiton premitive and migration to WID 6.2

I have used custom mediation primitive in WID 6.0.2 with implementation "invoke". When moved the code to WID 6.2 custome mediation primitive has only two types of implementations 1) Visual and 2) java. Previously coded custom mediation primitives are converted to simple java implementation with service lookup and service.invoke("operationName", argument)

At this moment, this may fail on runtime with argument smo.getBody(); not all times this may work. In such case use service invoke primitive which is introduced in WID 6.2