public String makeOauth2TokenRequest(String refreshToken) {
        var scope = this.getScope();
        if (StringUtils.isBlank(scope)){
            // default values
            scope = "openid profile email";
        }
        val payload = HttpUtils.encodeQueryParam("client_id",this.getClientId())
            + "&" + HttpUtils.encodeQueryParam("client_secret",this.getSecret())
            + "&" + HttpUtils.encodeQueryParam("grant_type","refresh_token")
            + "&" + HttpUtils.encodeQueryParam("refresh_token",refreshToken)
            + "&" + HttpUtils.encodeQueryParam("tenant", this.getTenant())
            + "&" + HttpUtils.encodeQueryParam("scope", scope);

        return payload;
    }
<p>makeOauth2TokenRequest.</p>

@param refreshToken a {@link String} object
@return a {@link String} object
pac4j-oidc/src/main/java/org/pac4j/oidc/config/AzureAd2OidcConfiguration.java