Special chars like "*" cannot be processed in enums

if an enum is generated from yang model that contains only a special character like "*" it fails to create working class for this enum.

as in https://tools.ietf.org/html/rfc8294 :
typedef ipv4-multicast-source-address {
type union {
type enumeration {
enum *

}
type inet:ipv4-address;
}
description
"Multicast source IPv4 address type.";
}