Text Entered in search textfield not passing in parameters

Hello,

Thank you in advance,

I have my own custom backend plugin where there is listing of employees, I also put search field to search the employee, when I type in search text field, it is executing the link like http://localhost/shopware_demo/backend/employee_plugin/reloadAssociation?_dc=111111111&id=1&association=employees&page=1&start=0&limit=20, but it is not appending parameters of text inputted in the search text field, I checked core plugin where I am able to see the parameters for search text like 

http://localhost/shopware_demo/backend/employee_plugin/reloadAssociation?_dc=1573119316162&page=1&start=0&limit=20&sort=[{"property"%3A"id"%2C"direction"%3A"DESC"}]&filter=[{"property"%3A"search"%2C"value"%3A"fsf"%2C"operator"%3Anull%2C"expression"%3Anull}]
but in my case there is only like

http://localhost/shopware_demo/backend/employee_plugin/reloadAssociation?_dc=1573119316162&page=1&start=0&limit=20&sort=[{"