Some guava tests

guava.java

    @Test
    public void validName() {
        String name = "Thomas";
        assertTrue(findInvalidChars(name, WhitelistCharacters.VALID_NAME_CHAR_SET).isEmpty());
    }

    @Test
    public void invalidName() {
        assertThat(findInvalidChars("<Thomas>", VALID_NAME_CHAR_SET), hasItems('<', '>'));
    }

    @Test
    public void prettyListOfInvalidChars() {
        String name = "<Th0mas>";
        assertEquals("<, 0, >", WhitelistCharacters.printChars(findInvalidChars(name, VALID_NAME_CHAR_SET)));
    }