diff --git a/java/google/registry/model/EppResourceUtils.java b/java/google/registry/model/EppResourceUtils.java
index 65a5a891e..24a8cf477 100644
--- a/java/google/registry/model/EppResourceUtils.java
+++ b/java/google/registry/model/EppResourceUtils.java
@@ -347,10 +347,12 @@ public final class EppResourceUtils {
   public static List<Key<DomainBase>> queryDomainsUsingResource(
       Class<? extends EppResource> clazz, Key<? extends EppResource> key, DateTime now, int limit) {
     checkArgument(ContactResource.class.equals(clazz) || HostResource.class.equals(clazz));
-    return ofy()
-        .load()
-        .type(DomainBase.class)
-        .filter(clazz.equals(ContactResource.class) ? "allContacts.contact" : "nsHosts", key)
+    return ofy().load().type(DomainBase.class)
+        .filter(
+            clazz.equals(ContactResource.class)
+                ? "allContacts.contactId.linked"
+                : "nameservers.linked",
+            key)
         .filter("deletionTime >", now)
         .limit(limit)
         .keys()
diff --git a/java/google/registry/model/domain/DesignatedContact.java b/java/google/registry/model/domain/DesignatedContact.java
index 96c3e8003..0712f42cf 100644
--- a/java/google/registry/model/domain/DesignatedContact.java
+++ b/java/google/registry/model/domain/DesignatedContact.java
@@ -72,6 +72,6 @@ public class DesignatedContact extends ImmutableObject {
   }
 
   public Key<ContactResource> getContactKey() {
-    return contact;
+    return contactId.getLinked();
   }
 }
diff --git a/java/google/registry/model/domain/DomainBase.java b/java/google/registry/model/domain/DomainBase.java
index 987618974..9c37eebda 100644
--- a/java/google/registry/model/domain/DomainBase.java
+++ b/java/google/registry/model/domain/DomainBase.java
@@ -183,7 +183,11 @@ public abstract class DomainBase extends EppResource {
   }
 
   public ImmutableSet<Key<HostResource>> getNameservers() {
-    return nullToEmptyImmutableCopy(nsHosts);
+    ImmutableSet.Builder<Key<HostResource>> builder = new ImmutableSet.Builder<>();
+    for (ReferenceUnion<HostResource> union : nullToEmptyImmutableCopy(nameservers)) {
+      builder.add(union.getLinked());
+    }
+    return builder.build();
   }
 
   /** Loads and returns the fully qualified host names of all linked nameservers. */
@@ -238,13 +242,13 @@ public abstract class DomainBase extends EppResource {
   @OnSave
   void dualSaveReferenceUnions() {
     for (DesignatedContact contact : nullToEmptyImmutableCopy(allContacts)) {
-      contact.contactId = ReferenceUnion.create(contact.contact);
+      contact.contact = contact.contactId.getLinked();
     }
-    ImmutableSet.Builder<ReferenceUnion<HostResource>> hosts = new ImmutableSet.Builder<>();
-    for (Key<HostResource> hostKey : nullToEmptyImmutableCopy(nsHosts)) {
-      hosts.add(ReferenceUnion.create(hostKey));
+    ImmutableSet.Builder<Key<HostResource>> hostKeys = new ImmutableSet.Builder<>();
+    for (ReferenceUnion<HostResource> refUnion : nullToEmptyImmutableCopy(nameservers)) {
+      hostKeys.add(refUnion.getLinked());
     }
-    nameservers = hosts.build();
+    nsHosts = hostKeys.build();
   }
 
   /** Predicate to determine if a given {@link DesignatedContact} is the registrant. */
@@ -303,7 +307,11 @@ public abstract class DomainBase extends EppResource {
     }
 
     public B setNameservers(ImmutableSet<Key<HostResource>> nameservers) {
-      getInstance().nsHosts = nameservers;
+      ImmutableSet.Builder<ReferenceUnion<HostResource>> builder = new ImmutableSet.Builder<>();
+      for (Key<HostResource> key : nullToEmpty(nameservers)) {
+        builder.add(ReferenceUnion.create(key));
+      }
+      getInstance().nameservers = builder.build();
       return thisCastToDerived();
     }
 
diff --git a/java/google/registry/rdap/RdapDomainSearchAction.java b/java/google/registry/rdap/RdapDomainSearchAction.java
index fb8912c38..15b2144bd 100644
--- a/java/google/registry/rdap/RdapDomainSearchAction.java
+++ b/java/google/registry/rdap/RdapDomainSearchAction.java
@@ -269,7 +269,7 @@ public class RdapDomainSearchAction extends RdapActionBase {
     for (List<Key<HostResource>> chunk : Iterables.partition(hostKeys, 30)) {
       for (DomainResource domain : ofy().load()
           .type(DomainResource.class)
-          .filter("nsHosts in", chunk)
+          .filter("nameservers.linked in", chunk)
           .filter("deletionTime >", now)
           .limit(rdapResultSetMaxSize + 1)) {
         if (!domains.contains(domain)) {
diff --git a/javatests/google/registry/model/domain/DomainApplicationTest.java b/javatests/google/registry/model/domain/DomainApplicationTest.java
index cbe4d2c0c..c76997ff2 100644
--- a/javatests/google/registry/model/domain/DomainApplicationTest.java
+++ b/javatests/google/registry/model/domain/DomainApplicationTest.java
@@ -145,16 +145,16 @@ public class DomainApplicationTest extends EntityTestCase {
 
   @Test
   public void testEmptySetsAndArraysBecomeNull() {
-    assertThat(emptyBuilder().setNameservers(null).build().nsHosts).isNull();
+    assertThat(emptyBuilder().setNameservers(null).build().nameservers).isNull();
     assertThat(emptyBuilder()
         .setNameservers(ImmutableSet.<Key<HostResource>>of())
         .build()
-        .nsHosts)
+        .nameservers)
             .isNull();
     assertThat(emptyBuilder()
         .setNameservers(ImmutableSet.of(Key.create(newHostResource("foo.example.tld"))))
         .build()
-        .nsHosts)
+        .nameservers)
             .isNotNull();
     // This behavior should also hold true for ImmutableObjects nested in collections.
     assertThat(emptyBuilder()
diff --git a/javatests/google/registry/model/domain/DomainResourceTest.java b/javatests/google/registry/model/domain/DomainResourceTest.java
index e15f8d8d3..3d7bfd4bd 100644
--- a/javatests/google/registry/model/domain/DomainResourceTest.java
+++ b/javatests/google/registry/model/domain/DomainResourceTest.java
@@ -207,13 +207,13 @@ public class DomainResourceTest extends EntityTestCase {
   @Test
   public void testEmptySetsAndArraysBecomeNull() {
     assertThat(newDomainResource("example.com").asBuilder()
-        .setNameservers(null).build().nsHosts).isNull();
+        .setNameservers(null).build().nameservers).isNull();
     assertThat(newDomainResource("example.com").asBuilder()
-        .setNameservers(ImmutableSet.<Key<HostResource>>of()).build().nsHosts)
+        .setNameservers(ImmutableSet.<Key<HostResource>>of()).build().nameservers)
             .isNull();
     assertThat(newDomainResource("example.com").asBuilder()
         .setNameservers(ImmutableSet.of(Key.create(newHostResource("foo.example.tld"))))
-            .build().nsHosts)
+            .build().nameservers)
                 .isNotNull();
     // This behavior should also hold true for ImmutableObjects nested in collections.
     assertThat(newDomainResource("example.com").asBuilder()
@@ -462,22 +462,21 @@ public class DomainResourceTest extends EntityTestCase {
   public void testDualSavingOfDesignatedContact() {
     ContactResource contact = persistActiveContact("time1006");
     DesignatedContact designatedContact = new DesignatedContact();
-    designatedContact.contact = Key.create(contact);
+    designatedContact.contactId = ReferenceUnion.create(Key.create(contact));
     designatedContact.type = Type.ADMIN;
     DomainResource domainWithContact =
         domain.asBuilder().setContacts(ImmutableSet.of(designatedContact)).build();
-    assertThat(getOnlyElement(domainWithContact.getContacts()).contactId).isNull();
+    assertThat(getOnlyElement(domainWithContact.getContacts()).contact).isNull();
     DomainResource reloadedDomain = persistResource(domainWithContact);
-    assertThat(getOnlyElement(reloadedDomain.getContacts()).contactId)
-        .isEqualTo(ReferenceUnion.create(Key.create(contact)));
+    assertThat(getOnlyElement(reloadedDomain.getContacts()).contact).isEqualTo(Key.create(contact));
   }
 
   @Test
   public void testDualSavingOfNameservers() {
     HostResource host = persistActiveHost("zzz.xxx.yyy");
     DomainResource domain = newDomainResource("python-django-unchained.com", host);
-    assertThat(domain.nameservers).isNull();
+    assertThat(domain.nsHosts).isNull();
     DomainResource djangoReloaded = persistResource(domain);
-    assertThat(djangoReloaded.nameservers).containsExactly(ReferenceUnion.create(Key.create(host)));
+    assertThat(djangoReloaded.nsHosts).containsExactly(Key.create(host));
   }
 }