Changes to POST /v1/contactBooks

added the new optional request property variables

added the optional property _count to the response with the 200 status

added the required property variables to the response with the 200 status

added the new optional request property doubleOptInContent

added the new optional request property doubleOptInEnabled

added the new optional request property doubleOptInFrom

added the new optional request property doubleOptInSubject

added the optional property doubleOptInContent to the response with the 200 status

added the optional property doubleOptInEnabled to the response with the 200 status

added the optional property doubleOptInFrom to the response with the 200 status

added the optional property doubleOptInSubject to the response with the 200 status

endpoint added

api path removed without deprecation