### Question:
StringUtil { public static boolean isBlank(final String strValue) { if (strValue == null) { return true; } return strValue.isBlank(); } private  StringUtil(); static boolean isBlank(final String strValue); static String first2LowerCase(final String strValue); static String first2UpperCase(final String strValue); static String constToLowerCamelCase(final String str); static String constToUpperCamelCase(final String str); static String camelToConstCase(final String str); static String camelToSnakeCase(final String str); static boolean isUpperCamelCase(final String testString); static boolean isLowerCamelCase(final String testString); static boolean isSimpleLetterOrDigit(final char c); static String replace(final String str, final String oldStr, final String newStr); static void replace(final StringBuilder str, final String oldStr, final String newStr); static String format(final String msg, final Object... params);  }### Answer:
@Test public void testIsEmpty() { assertTrue(StringUtil.isBlank(null)); assertTrue(StringUtil.isBlank("")); assertTrue(StringUtil.isBlank(" ")); assertFalse(StringUtil.isBlank("a")); assertFalse(StringUtil.isBlank(" a ")); }