public Map<String, List<String>> getCustomQueryParameters() {
        if (customQueryParameters == null) {
            return null;
        }
        return Collections.unmodifiableMap(customQueryParameters);
    }
@return the immutable map of custom query parameters. The parameter value is modeled as a
        list of strings because multiple values can be specified for the same parameter name.
aws-java-sdk-core/src/main/java/com/amazonaws/AmazonWebServiceRequest.java