### Question:
EagleEyeCoreUtils { public static StringBuilder appendWithBlankCheck(String str, String defaultValue, StringBuilder appender) { if (isNotBlank(str)) { appender.append(str); } else { appender.append(defaultValue); } return appender; }  static boolean isBlank(String str); static String checkNotNullEmpty(String value, String name); static T checkNotNull(T value, String name); static T defaultIfNull(T value, T defaultValue); static boolean isNotBlank(String str); static boolean isNotEmpty(String str); static String trim(String str); static String[] split(String str, char separatorChar); static StringBuilder appendWithBlankCheck(String str, String defaultValue, StringBuilder appender); static StringBuilder appendWithNullCheck(Object obj, String defaultValue, StringBuilder appender); static StringBuilder appendLog(String str, StringBuilder appender, char delimiter); static String formatTime(long timestamp); static String getSystemProperty(String key); static long getSystemPropertyForLong(String key, long defaultValue); static boolean isHexNumeric(char ch); static boolean isNumeric(char ch); static void shutdownThreadPool(ExecutorService pool, long awaitTimeMillis); @SuppressWarnings("restriction") static sun.misc.Unsafe getUnsafe(); static final String EMPTY_STRING; static final String NEWLINE; static final String[] EMPTY_STRING_ARRAY; }### Answer:
@Test public void testAppendWithBlankCheck() { Assert.assertEquals("bar", EagleEyeCoreUtils.appendWithBlankCheck( null, "bar", new StringBuilder()).toString()); Assert.assertEquals("foo", EagleEyeCoreUtils.appendWithBlankCheck( "foo", "bar", new StringBuilder()).toString()); }