Oracle SOA Suite 12c Invoking External WebService Error- Invalid Reference

Recently I had been working on some integration project where I need to invoke an external web service. Some strange thing happened with respect to SOA adapter configuration. Below are the steps-, 

1. Add a SOAP adapter [BPEL1.1]  and configure the web service WSDL url.
2. Add a BPEL component (in my case expose as a service)
3. Do wiring of a BPEL process with SOAP adapter.
4. Open the BPEL component and add invoke activity.
5. Drag invoke activity to SOAP web service and DO configure it by selecting the operation and creating input/output variables.
6. Do variables assignment.
7. Build the project.
8. Ohhh snap... Build failed with below error messages-

ERROR XML

Cause- The external Web Service WSDL (Which I am trying to invoke from BPEL) contains both import and element entries as part of different schema entries then the composite.xml is throwing 'Invalid reference' and 'message part undefined' errors as shown in the above thread. In addition upon WSDL observation, it clearly shows that PHXServletException element is outside its corresponding schema.However the external SOAP web service invocation from SOAP UI was successful but problem caused during the invocation from BPEL process

Solution-

If I keep both import and elements as part of one schema then composite.xml is recognizing the elements. As shown in above digram the PHXServletException element should be moved to corresponding import and schema. 

Ref- https://www.databaseusers.com/article/6076482/Invoking+external+service%3A+Getting+%27Invalid+reference%27+build+error