Hi; I will close this issue because OWB must not intercept private methods. Therefore its OK to not intercept private methods of producer, observer etc. It is reasonable because __private__ methods are not called by any other methods that are not defined in __target__ object.
I have also tried examples (private observer, private producer etc.) in RI Weld, it also does not intercept private methods. Therefore, I am going to close this issue. Thanks; --Gurkan