public Mono<AccessToken> getToken(TokenRequestContext request)  {
    Map<String, String> env = System.getenv();
    String clientAssertion = "<jwt>";

    IClientCredential credential = ClientCredentialFactory.createFromClientAssertion(clientAssertion);
    String authority = "...";
    try {
        ConfidentialClientApplication app = ConfidentialClientApplication.builder(env.get("AZURE_CLIENT_ID"), credential).authority(authority).build();

        Set<String> scopes = new HashSet<>();
        for (String scope : request.getScopes()) scopes.add(scope);

        ClientCredentialParameters parameters = ClientCredentialParameters.builder(scopes).build();
        IAuthenticationResult result = app.acquireToken(parameters).join();
        return Mono.just(new AccessToken(result.accessToken(), result.expiresOnDate().toInstant().atOffset(ZoneOffset.UTC)));
    } catch (Exception e) {
        System.out.printf("Error creating client application: %s", e.getMessage());
        System.exit(1);
    }

    return Mono.empty();
}