### Question:
AmazonHttpClient { static String createUserAgentString(String existingUserAgentString, String userAgent) { if (existingUserAgentString.contains(userAgent)) { return existingUserAgentString; } else { return existingUserAgentString.trim() + " " + userAgent.trim(); } } AmazonHttpClient(ClientConfiguration config); @Deprecated  AmazonHttpClient(ClientConfiguration config,
            RequestMetricCollector requestMetricCollector);  AmazonHttpClient(ClientConfiguration config, HttpClient httpClient); @Deprecated  AmazonHttpClient(ClientConfiguration config, HttpClient httpClient,
            RequestMetricCollector requestMetricCollector); @Deprecated ResponseMetadata getResponseMetadataForRequest(AmazonWebServiceRequest request); Response<T> execute(Request<?> request,
            HttpResponseHandler<AmazonWebServiceResponse<T>> responseHandler,
            HttpResponseHandler<AmazonServiceException> errorResponseHandler,
            ExecutionContext executionContext); void shutdown(); RequestMetricCollector getRequestMetricCollector();  }### Answer:
@Test public void testCreateUserAgent() { String existingUA = "Existing"; String additionalUA = "Additional"; String ua = AmazonHttpClient.createUserAgentString(existingUA, additionalUA); assertEquals(ua, (existingUA + " " + additionalUA)); }
@Test public void testCreateUserAgentWithDuplicateAddition() { String existingUA = "Existing"; String additionalUA = "Existing"; String ua = AmazonHttpClient.createUserAgentString(existingUA, additionalUA); assertEquals(ua, (existingUA)); }