static String convertEnvVars(String input){
        // check for any non-alphanumeric chars and convert to underscore
        // convert to upper case
        if (input == null) {
            return null;
        }
        return input.replaceAll("[^A-Za-z0-9]", "_").toUpperCase();
    }
@Test
    public void testConvertEnvVarsUsingNullValue() {
        String testInput2 = ConfigInjection.convertEnvVars(null);
        Assert.assertEquals(null, testInput2);
    }