### Question:
StringUtils extends org.apache.commons.lang3.StringUtils { public static String toCapitalizeCamelCase(String s) { if (s == null) { return null; } s = toCamelCase(s); return s.substring(0, 1).toUpperCase() + s.substring(1); }  static String toCamelCase(String s); static String toCapitalizeCamelCase(String s); static String getIp(HttpServletRequest request); static String getCityInfo(String ip); static String getHttpCityInfo(String ip); static String getLocalCityInfo(String ip); static String getBrowser(HttpServletRequest request); static String getWeekDay(); static String getLocalIp();  }### Answer:
@Test public void testToCapitalizeCamelCase() { assertNull(StringUtils.toCapitalizeCamelCase(null)); assertEquals("HelloWorld", toCapitalizeCamelCase("hello_world")); }