dav: Move displayname to common properties

crates/carddav/src/principal/mod.rs

@@ -54,12 +54,6 @@ impl Resource for PrincipalResource {
         Ok(match prop {
             PrincipalPropWrapperName::Principal(prop) => {
                 PrincipalPropWrapper::Principal(match prop {
-                    PrincipalPropName::Displayname => PrincipalProp::Displayname(
-                        self.principal
-                            .displayname
-                            .to_owned()
-                            .unwrap_or(self.principal.id.to_owned()),
-                    ),
                     PrincipalPropName::PrincipalUrl => PrincipalProp::PrincipalUrl(principal_href),
                     PrincipalPropName::AddressbookHomeSet => {
                         PrincipalProp::AddressbookHomeSet(home_set)
@@ -74,6 +68,15 @@ impl Resource for PrincipalResource {
         })
     }
 
+    fn get_displayname(&self) -> Option<&str> {
+        Some(
+            self.principal
+                .displayname
+                .as_ref()
+                .unwrap_or(&self.principal.id),
+        )
+    }
+
     fn get_owner(&self) -> Option<&str> {
         Some(&self.principal.id)
     }

crates/carddav/src/principal/prop.rs

@@ -7,9 +7,6 @@ pub struct AddressbookHomeSet(#[xml(ty = "untagged", flatten)] pub(super) Vec<Hr
 #[derive(XmlDeserialize, XmlSerialize, PartialEq, Clone, EnumVariants, PropName)]
 #[xml(unit_variants_ident = "PrincipalPropName")]
 pub enum PrincipalProp {
-    #[xml(ns = "rustical_dav::namespace::NS_DAV")]
-    Displayname(String),
-
     // WebDAV Access Control (RFC 3744)
     #[xml(rename = b"principal-URL")]
     #[xml(ns = "rustical_dav::namespace::NS_DAV")]