Webservices onboarding error during PUT request, plan contains the add/remove but JSON body empty

Webservices onboarding error during PUT request, plan contains the add/remove but JSON body empty.
I am trying to send a PUT request but JSON body in requestendpoint is empty.
This application has three different entitlements so while configuring the add entitlement, do I need three add entitlement/remove entitlement operations or one is enough.
Even if I add three or one I am getting same 500 error as the jsonbody in requestendpoint is coming empty.