### Question:
DockerCloudUtils { @Nonnull public static String getStackTrace(@Nullable Throwable throwable) { if (throwable == null) { return ""; } StringWriter sw = new StringWriter(); try (PrintWriter pw = new PrintWriter(sw)) { throwable.printStackTrace(pw); } return sw.toString(); }  @Nonnull static T requireNonNull(T obj, @Nonnull String msg); @Nonnull static T requireNonNull(T obj, @Nonnull Supplier<String> msgSupplier); @Nullable static UUID getClientId(@Nonnull AgentDescription agentDescription); @Nullable static UUID getImageId(@Nonnull AgentDescription agentDescription); @Nullable static UUID getInstanceId(@Nonnull AgentDescription agentDescription); @Nullable static UUID tryParseAsUUID(@Nullable String value); @Nonnull static String toShortId(@Nonnull String id); @Nonnull static Logger getLogger(@Nonnull Class<?> cls); @Nullable static String getEnvParameter(@Nonnull AgentDescription agentDescription, @Nonnull String name); @Nonnull static String readUTF8String(@Nonnull InputStream inputStream); @Nonnull static String readUTF8String(@Nonnull InputStream inputStream, int maxByteLength); static boolean hasImageTag(@Nonnull String image); static long toUnsignedLong(int value); @Nonnull static String getStackTrace(@Nullable Throwable throwable); @Nonnull static Map<String, String> extractTCPluginParams(@Nonnull HttpServletRequest request); static boolean isDebugEnabled(); static boolean isDefaultDockerSocketAvailable(); static boolean isDefaultDockerNamedPipeAvailable(); static boolean isWindowsHost(); @Nonnull @SafeVarargs static Map<K,V> immutableMapOf(@Nonnull Pair<K,V>... pairs); @Nonnull @SafeVarargs static Map<K,V> mapOf(@Nonnull Pair<K,V>... pairs); @Nonnull static Pair<K,V> pair(@Nonnull K key, @Nonnull V value); static final String NS; static final String NS_PREFIX; static final String CLIENT_ID_LABEL; static final String INSTANCE_ID_LABEL; static final String SOURCE_IMAGE_ID_LABEL; static final String TEST_INSTANCE_ID_LABEL; static final String CLOUD_TYPE_PARAM; static final String CLIENT_UUID_PARAM; static final String SERVER_URL_PARAM; static final String IMAGES_PARAM; static final String TEST_IMAGE_PARAM; static final String USE_DEFAULT_UNIX_SOCKET_PARAM; static final String USE_DEFAULT_WIN_NAMED_PIPE_PARAM; static final String INSTANCE_URI; static final String USE_TLS; static final String AGENT_RUNTIME_ID_AGENT_CONF; static final URI DOCKER_DEFAULT_SOCKET_URI; static final URI DOCKER_DEFAULT_NAMED_PIPE_URI; static final DockerAPIVersion DOCKER_API_TARGET_VERSION; static final DockerAPIVersion DOCKER_API_MIN_VERSION; static final String DEBUG_SYSPROP; static final String ENV_PREFIX; static final String ENV_CLIENT_ID; static final String ENV_IMAGE_ID; static final String ENV_INSTANCE_ID; static final String ENV_AGENT_PARAMS; static final String ENV_TEST_INSTANCE_ID; static final String ENV_SERVER_URL; static final String TC_PROPERTY_PREFIX; }### Answer:
@Test public void getStackTrace() { assertThat(DockerCloudUtils.getStackTrace(new RuntimeException("test"))). isNotEmpty(); }
@Test public void getStackTraceWithNullInput() { assertThat(DockerCloudUtils.getStackTrace(null)).isEmpty(); }