presto-elasticsearch/src/main/java/io/prestosql/elasticsearch/client/ElasticsearchClient.java/ElasticsearchClient/getAwsCredentialsProvider
class ElasticsearchClient:    private static AWSCredentialsProvider getAwsCredentialsProvider(AwsSecurityConfig config)
    {
        if (config.getAccessKey().isPresent() && config.getSecretKey().isPresent()) {
            return new AWSStaticCredentialsProvider(new BasicAWSCredentials(
                    config.getAccessKey().get(),
                    config.getSecretKey().get()));
        }
        if (config.isUseInstanceCredentials()) {
            return InstanceProfileCredentialsProvider.getInstance();
        }
        return DefaultAWSCredentialsProviderChain.getInstance();
    }