### Question:
CbStrings { public static String nullToEmpty(String s) { return s == null ? "" : s; } private  CbStrings(); static String nullToEmpty(String s); static String emptyToNull(String s); static boolean isNullOrEmpty(String s); static String removeStart(String s, String removeMe); static String removeEnd(String s, String removeMe);  }### Answer:
@Test void nullToEmpty() { assertEquals("", CbStrings.nullToEmpty(null)); assertEquals("", CbStrings.nullToEmpty("")); assertEquals("xyzzy", CbStrings.nullToEmpty("xyzzy")); }