OKTA is not able to verify APPIAN using event Hooks.

Okay This i was testing as i have not checked the box .. so it inot giving the value 

But ideally Scenario 

In get call OKTA is going to send the x-okta-verification-challenge :<>

Which needs to be send in the request Body of the Get call .{as per the okta document https://developer.okta.com/docs/concepts/event-hooks/#one-time-verification-request }

Can you change the header name for authentication, OKTA is using to "Appian-API-Key"?

Is there any way to log request in appian ?

I know. Appian is very specific about this. When you use the header "Authorization", you must adhere to this

• Appian-API-Key Header:
  curl example.appian.com/.../endpoint -H "Appian-API-Key: ${API_KEY}"

• Bearer Token Header:
  curl example.appian.com/.../endpoint -H "Authorization: Bearer ${API_KEY}"

• Basic Authentication Header (with null username):
  curl -u :${API_KEY} example.appian.com/.../endpoint

• Basic Authentication Header (with null password):
  curl -u ${API_KEY}: example.appian.com/.../endpoint

I mean the colon before or after the key.

Above screen is Okta where i am passing Option 1 which working. But since i don't know what request i am getting can't filter the verification values 

• Appian-API-Key Header:
  curl example.appian.com/.../endpoint -H "Appian-API-Key: ${API_KEY}"

  is there any way to log the Get request in APPIAN ?? 

AFAIK there is no detailed logging in Appian by default. If required, you can open a support case and ask for assistance from the cloud team.