@GetMapping({
        '/' + OidcConstants.BASE_OIDC_URL + '/' + OAuth20Constants.AUTHORIZE_URL,
        "/**/" + OidcConstants.AUTHORIZE_URL
    })
    @Operation(summary = "Handle OIDC authorization request")
    @Override
    public ModelAndView handleRequest(final HttpServletRequest request, final HttpServletResponse response) throws Throwable {
        val webContext = new JEEContext(request, response);
        if (!getConfigurationContext().getIssuerService().validateIssuer(webContext, List.of(OidcConstants.AUTHORIZE_URL, OAuth20Constants.AUTHORIZE_URL))) {
            LOGGER.warn("CAS cannot accept the authorization request given the issuer is invalid.");
            return OAuth20Utils.writeError(response, OAuth20Constants.INVALID_REQUEST, "Invalid issuer");
        }

        if (getConfigurationContext().getDiscoverySettings().isRequirePushedAuthorizationRequests()
            && webContext.getRequestURL().endsWith(OidcConstants.AUTHORIZE_URL)
            && StringUtils.isBlank(request.getParameter(OidcConstants.REQUEST_URI))) {
            LOGGER.warn("CAS is configured to only accept pushed authorization requests");
            return OAuth20Utils.produceUnauthorizedErrorView(HttpStatus.FORBIDDEN);
        }

        val scopes = getConfigurationContext().getRequestParameterResolver().resolveRequestedScopes(webContext);
        if (scopes.isEmpty() || !scopes.contains(OidcConstants.StandardScopes.OPENID.getScope())) {
            LOGGER.warn("Provided scopes [{}] are undefined by OpenID Connect, which requires that scope [{}] MUST be specified, "
                        + "or the behavior is unspecified. CAS MAY allow this request to be processed for now.",
                scopes, OidcConstants.StandardScopes.OPENID.getScope());
        }
        return super.handleRequest(request, response);
    }
This is {@link OidcAuthorizeEndpointController}.

@author Misagh Moayyed
@since 5.0.0
support/cas-server-support-oidc-core-api/src/main/java/org/apereo/cas/oidc/web/controllers/authorize/OidcAuthorizeEndpointController.java