public Optional<Output<String>> externalName() {
        return Optional.ofNullable(this.externalName);
    }
@return externalName is the external reference that discovery mechanisms will return as an alias for this service (e.g. a DNS CNAME record). No proxying will be involved.  Must be a lowercase RFC-1123 hostname (https://tools.ietf.org/html/rfc1123) and requires `type` to be &#34;ExternalName&#34;.
sdk/java/src/main/java/com/pulumi/kubernetes/core/v1/inputs/ServiceSpecArgs.java