### Question:
JsonEscapeHelper { @Nonnull public static String jsonUnescape (@Nonnull final String sInput) { ValueEnforcer.notNull (sInput, "Input"); if (sInput.indexOf (MASK_CHAR) < 0) { return sInput; } final StringBuilder aSB = new StringBuilder (sInput.length ()); jsonUnescapeToStringBuilder (sInput.toCharArray (), aSB); return aSB.toString (); } private  JsonEscapeHelper(); static void jsonEscapeToStringBuilder(@Nonnull final char [] aInput, @Nonnull final StringBuilder aSB); @Nullable static String jsonEscape(@Nullable final String sInput); @Nullable static String jsonEscape(@Nullable final char [] aInput); static void jsonEscape(@Nullable final String sInput, @Nonnull final StringBuilder aSB); static void jsonEscapeToWriter(@Nonnull final char [] aInput, @Nonnull @WillNotClose final Writer aWriter); static void jsonEscapeToWriter(@Nullable final String sInput, @Nonnull @WillNotClose final Writer aWriter); static void jsonUnescapeToStringBuilder(@Nonnull final char [] aInput, @Nonnull final StringBuilder aSB); @Nonnull static String jsonUnescape(@Nonnull final String sInput); @Nonnull static String jsonUnescape(@Nonnull final char [] aInput); static final char MASK_CHAR; static final String MASK_STRING; }### Answer:
@Test public void testUnscape () { assertEquals (STRING_UNESCAPED, JsonEscapeHelper.jsonUnescape (STRING_ESCAPED)); assertEquals ("", JsonEscapeHelper.jsonUnescape ("")); }