protected int skipWhiteSpace(int i, String s) {
        for (; i < s.length() && (s.charAt(i) == ' ' || s.charAt(i) == '\t'); i++) {
            ;
        }

        return i;
    }
Indicates whether the specified cron expression can be parsed into a
valid cron expression

@param cronExpression the expression to evaluate
@return a boolean indicating whether the given expression is a valid cron
        expression
lts-core/src/main/java/com/github/ltsopensource/core/support/CronExpression.java