Eliminate models.StringsToNameservers() (#1486)

* Eliminate StringsToNameservers()

* update comments

models/dns.go

@@ -43,32 +43,23 @@ type DNSProviderConfig struct {
 	Metadata json.RawMessage `json:"meta,omitempty"`
 }
 
-// FIXME(tal): In hindsight, the Nameserver struct is overkill. We
-// could have just used []string.  Now every provider calls StringsToNameservers
-// and ever user calls StringsToNameservers.  We should refactor this
-// some day.  https://github.com/StackExchange/dnscontrol/issues/577
-
 // Nameserver describes a nameserver.
 type Nameserver struct {
 	Name string `json:"name"` // Normalized to a FQDN with NO trailing "."
 	// NB(tlim): DomainConfig.Nameservers are stored WITH a trailing "." (Sorry!)
 }
 
+// FIXME(tal): In hindsight the Nameserver struct is overkill. We
+// could have just used string.  Currently there are very few places
+// that refer to the .Name field directly.  All new code should use
+// ToNameservers/ToNameserversStripTD and NameserversToStrings to make
+// future refactoring easier.  See
+// https://github.com/StackExchange/dnscontrol/issues/577
+
 func (n *Nameserver) String() string {
 	return n.Name
 }
 
-// StringsToNameservers constructs a list of *Nameserver structs using a list of FQDNs.
-// Deprecated. Please use ToNameservers, or maybe ToNameserversStripTD instead.
-// See https://github.com/StackExchange/dnscontrol/issues/491
-func StringsToNameservers(nss []string) []*Nameserver {
-	nservers := []*Nameserver{}
-	for _, ns := range nss {
-		nservers = append(nservers, &Nameserver{Name: ns})
-	}
-	return nservers
-}
-
 // ToNameservers turns a list of strings into a list of Nameservers.
 // It is an error if any string has a trailing dot. Either remove the
 // trailing dot before you call this or (much preferred) use ToNameserversStripTD.