private static void explicit_encrypt_bug () {
        Map kmsProviders = new HashMap();
        Map awsCreds = new HashMap();
        if (System.getenv().get("AWS_ACCESS_KEY_ID") == null || System.getenv().get("AWS_SECRET_ACCESS_KEY") == null) {
            throw new IllegalArgumentException("no aws creds set");
        }
        awsCreds.put("accessKeyId", System.getenv().get("AWS_ACCESS_KEY_ID"));
        awsCreds.put("secretAccessKey", System.getenv().get("AWS_SECRET_ACCESS_KEY"));
        kmsProviders.put ("aws", awsCreds);

        ClientEncryptionSettings clientEncryptionSettings = ClientEncryptionSettings.builder().
                keyVaultMongoClientSettings(MongoClientSettings.builder().build()).
                kmsProviders(kmsProviders).
                keyVaultNamespace("admin.datakeys").build();
        ClientEncryption clientEncryption = ClientEncryptions.create (clientEncryptionSettings);
        EncryptOptions opts = new EncryptOptions("AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic");
        opts.keyAltName(new BsonString("mykey"));
        System.out.println(clientEncryption.encrypt(new BsonString("123456789"), opts));
    }

Exception in thread "main" java.lang.NullPointerException
	at com.mongodb.crypt.capi.MongoCryptImpl.createExplicitEncryptionContext(MongoCryptImpl.java:209)
	at com.mongodb.client.internal.Crypt.encryptExplicitly(Crypt.java:176)
	at com.mongodb.client.internal.ClientEncryptionImpl.encrypt(ClientEncryptionImpl.java:60)
	at Runner.explicit_encrypt_bug(Runner.java:257)
	at Runner.main(Runner.java:262)