in src/main/java/com/amazonaws/neptune/auth/NeptuneSigV4SignerBase.java [94:98]
public NeptuneSigV4SignerBase(final String regionName,
final AWSCredentialsProvider v1AwsCredentialProvider) throws NeptuneSigV4SignerException {
// Use neptune-db as default service name
this(regionName, v1AwsCredentialProvider, NEPTUNE_SERVICE_NAME);
}