private static String retryDateSuggestionIfExists(Date retryDateSuggestion) {
        if (retryDateSuggestion == null) {
            return "";
        } else {
            return ", suggested retry date is " + retryDateSuggestion;
        }
    }
Returns a {@link Date} suggestion when a particular {@link Reason} should no longer be valid

@return the date suggestion or null if no suggestion available
rxandroidble/src/main/java/com/polidea/rxandroidble2/exceptions/BleScanException.java