### Question:
StringUtils { public static boolean isBlank(final CharSequence cs) { int strLen; if (cs == null || (strLen = cs.length()) == 0) { return true; } for (int i = 0; i < strLen; i++) { if (Character.isWhitespace(cs.charAt(i)) == false) { return false; } } return true; } private  StringUtils(); static boolean isBlank(final CharSequence cs); static boolean isNotBlank(final CharSequence cs); static String getMaskedString(String secret, int lastSymbolsCount); static String getMaskedString(String secret); static String defaultIfBlank(String value, String defaultValue);  }### Answer:
@Test void isBlank() { assertThat(StringUtils.isBlank(null), is(true)); assertThat(StringUtils.isBlank(""), is(true)); assertThat(StringUtils.isBlank(" "), is(true)); assertThat(StringUtils.isBlank("bob"), is(false)); assertThat(StringUtils.isBlank(" bob "), is(false)); }