private static boolean isAlphanumeric(char c) {
        return (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9');
    }
Checks if the given hostLabel string is a virtual hostable bucket name.

@param hostLabel Host label to check.
@param allowDots Whether to allow dots in the host label.
@return true if it is compatible.
smithy-aws-endpoints/src/main/java/software/amazon/smithy/rulesengine/aws/language/functions/IsVirtualHostableS3Bucket.java