@Test
    public void testInvalidCustomTz() {
        TZ_CUSTOM_INVALID.forEach((tzStr) -> {
            try {
                String tzId = WHERE_IN_WORLD.parseValue(tzStr).getID();
                fail("Invalid custom time zone value \"" + tzStr + "\" for TimeZoneGuacamoleProperty should fail to parse with an exception.");
            }
            catch (GuacamoleException e) {
                String msg = e.getMessage();
                assertTrue(msg.contains("does not specify a valid time zone"));
            }
        });
    }
Tests several invalid custom timezone offsets to make sure that they are
not accepted as valid timezones.
guacamole-ext/src/test/java/org/apache/guacamole/properties/TimeZoneGuacamolePropertyTest.java