Use Cow for NameServers::ns

src/domain/create.rs

@@ -58,7 +58,7 @@ impl<'a> DomainCreate<'a> {
             domain: DomainCreateRequestData {
                 name,
                 period,
-                ns: ns.map(|ns| NameServers { ns: ns.to_vec() }),
+                ns: ns.map(|ns| NameServers { ns: ns.into() }),
                 registrant,
                 auth_info: DomainAuthInfo::new(auth_password),
                 contacts,

src/domain/mod.rs

@@ -130,7 +130,7 @@ pub enum HostInfo<'a> {
 #[derive(Debug, FromXml, ToXml)]
 #[xml(rename = "ns", ns(XMLNS))]
 pub struct NameServers<'a> {
-    pub ns: Vec<HostInfo<'a>>,
+    pub ns: Cow<'a, [HostInfo<'a>]>,
 }
 
 /// The &lt;contact&gt; type on domain creation and update requests