Hi,
Follow below steps and Check
* Load the blackened api wsdl/swagger/wadl to Soap UI , Change the Endpoint to Gateway i.e. which you will enter in proxy field while API creation(Note- API path should be unique)
* Export the swagger/wadl from Soap Ui
* Create new API on portal(In proxy url enter gateway url i.e. one entered while creating swagger/wadl and in Location- Enter blackened URL
* On Gateway- Check weather API is synchronised or not, once done check using Soap UI weather you are able to get proper response from newly created API or not
* Now Go to API explorer and Check
Regards,
Mahesh