Hi Atul,
As Per my understanding of the above issue, You need to run the search of the bussiness partner which is having the selection parameter 'Source' attribute as a default one and it should not be visible in the Search View.
Please correct it if i am correct.
If i am correct, Then you need to remove the attribute from the Search view configuration and then please keep the Code which you have added in the EH_ONSEARCH() method by passing the default value for the selection criteria for this newly added attribute.
Regards,
Rajyalakshmi CH