You can:
You need to verify the phone number you want to use to send messages to your customers. Phone numbers must be verified through SMS/voice call. The verification process can be done through this library.
See the examples:
WhatsappApiFactory factory = WhatsappApiFactory.newInstance();
WhatsappBusinessManagementApi whatsappBusinessManagementApi = factory.newBusinessManagementApi(TestConstants.TOKEN);
var response = whatsappBusinessManagementApi.requestCode(TestConstants.PHONE_NUMBER_ID, new RequestCode(CodeMethodType.SMS, LanguageType.EN_US));
System.out.println(response);
WhatsappApiFactory factory = WhatsappApiFactory.newInstance();
WhatsappBusinessManagementApi whatsappBusinessManagementApi = factory.newBusinessManagementApi(TestConstants.TOKEN);
var response2 = whatsappBusinessManagementApi.verifyCode(TestConstants.PHONE_NUMBER_ID, new VerifyCode("0000"));
System.out.println(response2);
See full examples here