private String readToken(String tokenFile) {
            try {
                byte[] bytes = Files.readAllBytes(FileSystems.getDefault().getPath(tokenFile));
                return new String(bytes, StringUtils.UTF8);
            } catch (IOException e) {
                throw new SdkClientException(
                        String.format("Cannot fetch credentials from container - failed to read %s", tokenFile));
            }
        }
A URI resolver that uses environment variable {@value CONTAINER_CREDENTIALS_FULL_URI} as the URI
for the metadata service.
Optionally an authorization token can be provided using the {@value CONTAINER_AUTHORIZATION_TOKEN} environment variable.
aws-java-sdk-core/src/main/java/com/amazonaws/auth/ContainerCredentialsProvider.java