private void assertParameterNotNull(Object parameterValue,
            String errorMessage) {
        if (parameterValue == null)
            throw new IllegalArgumentException(errorMessage);
    }
Creates and returns a new instance of Amazon Web Services KMS client in the case when
an explicit Amazon Web Services KMS client is not specified.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/AmazonS3EncryptionClient.java