How can I use "callbackUrl" rather than "redirect_uri" as the key of my callback url.

[janjian]

the authorization server using key: callbackUrl to receive redirect_uri in Oauth2.0.
the project has been using redirect_uri as:
if (redirectUri != null) {
form.set("redirect_uri", redirectUri);
}
how can i change the key of my redirectUri, using "callbackUrl" rather than "redirect_uri".