I have a non IAM neptune cluster configured , I am using Management API to fetch the cluster details i want to know if the instance is IAM enabled or disabled.
I am using below code to get amazon neptune instance.

AmazonNeptune neptuneClient=    AmazonNeptuneClientBuilder.standard().withRegion("region-name").build();

        DescribeDBClustersRequest describeDBClustersRequest = new DescribeDBClustersRequest()
                .withDBClusterIdentifier("cluster - endpoint");
        DescribeDBClustersResult describeDBClustersResult = neptuneClient
                .describeDBClusters(describeDBClustersRequest);
        for (DBCluster cluster : describeDBClustersResult.getDBClusters()) {
            boolean iamEnabled = cluster.getIAMDatabaseAuthenticationEnabled();
            System.out.println("IAM authentication enabled for cluster '" + clusterIdentifier + "': " + iamEnabled);

        }

As its non IAM i am not passing credentials ,but its giving exception for AWS credentials as below –

com.amazonaws.SdkClientException: Unable to load AWS credentials from any provider in the chain: [EnvironmentVariableCredentialsProvider: Unable to load AWS credentials from environment variables (AWS_ACCESS_KEY_ID (or AWS_ACCESS_KEY) and AWS_SECRET_KEY (or AWS_SECRET_ACCESS_KEY)), SystemPropertiesCredentialsProvider: Unable to load AWS credentials from Java system properties (aws.accessKeyId and aws.secretKey), WebIdentityTokenCredentialsProvider: To use assume role profiles the aws-java-sdk-sts module must be on the class path., com.amazonaws.auth.profile.ProfileCredentialsProvider@7c22d4f: profile file cannot be null, com.amazonaws.auth.EC2ContainerCredentialsProviderWrapper@664a9613: Failed to connect to service endpoint: ]
at com.amazonaws.auth.AWSCredentialsProviderChain.getCredentials(AWSCredentialsProviderChain.java:136)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.getCredentialsFromContext(AmazonHttpClient.java:1257)