StringToCharArrayConverter implements StringConverter<char[]> { @Override public char[] convert(String source) { return isNotEmpty(source) ? source.toCharArray() : null; }  @Override char[] convert(String source); @Override int getPriority();  }
@Test public void testConvert() { assertArrayEquals(new char[]{'1', '2', '3'}, converter.convert("123")); assertNull(converter.convert(null)); }