static void setOauth2Context(ServiceRequestContext ctx, OAuth2TokenDescriptor tokenDescriptor,
                                 @Nullable String realm) {
        ctx.setAttr(OAUTH2_TOKEN, tokenDescriptor);
        if (realm != null) {
            ctx.setAttr(OAUTH2_REALM, realm);
        }
    }
Sets the OAuth 2 token to the request context for optional application-level validation.
oauth2/src/main/java/com/linecorp/armeria/server/auth/oauth2/OAuth2TokenScopeValidator.java