customResponseBodyKey

References the response body that you want WAF to return to the web request client. You can define a custom response for a rule action or a default web ACL action that is set to block. To do this, you first define the response body key and value in the CustomResponseBodies setting for the WebACL or RuleGroup where you want to use it. Then, in the rule action or web ACL default action BlockAction setting, you reference the response body using this key.