### Question:
CommonHelper { public static <T extends Enum<T>> ReferencedOptional<T> findEnumField(Class<T> enumClass, String field) { Map<String, WeakReference<? extends Enum<?>>> cached = CACHE.computeIfAbsent(enumClass, aClass -> cache(enumClass)); WeakReference<? extends Enum<?>> reference = cached.get(field.toUpperCase()); return reference == null ? ReferencedOptional.empty() : ReferencedOptional.build(enumClass.cast(reference.get())); } private  CommonHelper(); static MemoryMXBean memoryMXBean(); static ClassLoadingMXBean classLoadingMXBean(); static OperatingSystemMXBean operatingSystemMXBean(); static RuntimeMXBean runtimeMXBean(); static ThreadMXBean threadMXBean(); static long memoryPoolMXBeanCollectionUsage(); static Integer fromString(String s); static Boolean booleanFromString(String s); static Long longFromString(String s); static UUID tryParse(String s); static int longToInt(long in); static int calculateMaxMemory(); static int getTotalSystemMemory(); static String getIpAddress(@NotNull String input); static @Unmodifiable @NotNull Collection<String> getAllAvailableIpAddresses(); static void setSystemPropertyIfUnset(@NotNull String property, @NotNull String value); static @NotNull String formatThrowable(@NotNull Throwable throwable); static ReferencedOptional<T> findEnumField(Class<T> enumClass, String field); static final ExecutorService EXECUTOR; static final ScheduledExecutorService SCHEDULED_EXECUTOR_SERVICE; static final ArrayDeque<String> EMPTY_STRING_QUEUE; static final DateFormat DATE_FORMAT; static final DecimalFormat DECIMAL_FORMAT; }### Answer:
@Test void testFindEnumField() { Version version = CommonHelper.findEnumField(Version.class, "paper_1_8_8").orNothing(); Assertions.assertNotNull(version); Assertions.assertEquals(Version.PAPER_1_8_8, version); Version version1 = CommonHelper.findEnumField(Version.class, "paper_1_4_9").orNothing(); Assertions.assertNull(version1); }