Run Address validation on GSON deserialization too

core/src/main/java/google/registry/model/eppcommon/Address.java

@@ -155,6 +155,7 @@ public Builder<? extends Address> asBuilder() {
 
   @Override
   public void postProcess() {
+    validateState();
     if (street == null || street.isEmpty()) {
       return;
     }
@@ -163,6 +164,21 @@ public void postProcess() {
     streetLine3 = street.size() >= 3 ? street.get(2) : null;
   }
 
+  public void validateState() {
+    checkArgument(
+        street == null || (!street.isEmpty() && street.size() <= 3),
+        "Street address must have [1-3] lines: %s",
+        street);
+    //noinspection ConstantConditions
+    checkArgument(
+        street == null || street.stream().noneMatch(String::isEmpty),
+        "Street address cannot contain empty string: %s",
+        street);
+    checkArgument(
+        countryCode == null || countryCode.length() == 2,
+        "Country code should be a 2 character string");
+  }
+
   /** A builder for constructing {@link Address}. */
   public static class Builder<T extends Address> extends Buildable.Builder<T> {
 
@@ -172,16 +188,13 @@ protected Builder(T instance) {
       super(instance);
     }
 
+    @Override
+    public T build() {
+      getInstance().validateState();
+      return super.build();
+    }
+
     public Builder<T> setStreet(ImmutableList<String> street) {
-      checkArgument(
-          street == null || (!street.isEmpty() && street.size() <= 3),
-          "Street address must have [1-3] lines: %s",
-          street);
-      //noinspection ConstantConditions
-      checkArgument(
-          street.stream().noneMatch(String::isEmpty),
-          "Street address cannot contain empty string: %s",
-          street);
       getInstance().street = street;
       getInstance().streetLine1 = street.get(0);
       getInstance().streetLine2 = street.size() >= 2 ? street.get(1) : null;

core/src/main/java/google/registry/model/registrar/RegistrarAddress.java

@@ -37,21 +37,20 @@ public Builder asBuilder() {
     return new Builder(clone(this));
   }
 
+  @Override
+  public void validateState() {
+    super.validateState();
+    checkNotNull(forceEmptyToNull(getStreet()), "Missing street");
+    checkNotNull(getCity(), "Missing city");
+    checkNotNull(getCountryCode(), "Missing country code");
+  }
+
   /** Builder for {@link RegistrarAddress}. */
   public static class Builder extends Address.Builder<RegistrarAddress> {
     public Builder() {}
 
     private Builder(RegistrarAddress instance) {
       super(instance);
     }
-
-    @Override
-    public RegistrarAddress build() {
-      RegistrarAddress instance = getInstance();
-      checkNotNull(forceEmptyToNull(instance.getStreet()), "Missing street");
-      checkNotNull(instance.getCity(), "Missing city");
-      checkNotNull(instance.getCountryCode(), "Missing country code");
-      return super.build();
-    }
   }
 }

core/src/test/java/google/registry/model/eppcommon/AddressTest.java

@@ -25,6 +25,7 @@
 import google.registry.model.eppcommon.AddressTest.TestEntity.TestAddress;
 import google.registry.persistence.transaction.JpaTestExtensions;
 import google.registry.persistence.transaction.JpaTestExtensions.JpaUnitTestExtension;
+import google.registry.tools.GsonUtils;
 import jakarta.persistence.Embeddable;
 import jakarta.persistence.Entity;
 import jakarta.persistence.Id;
@@ -124,6 +125,38 @@ void testSuccess_pojoToAndFromXml() throws Exception {
     assertAddress(unmarshalledEntity.address, "123 W 14th St", "8th Fl", "Rm 8");
   }
 
+  @Test
+  void testSuccess_gsonInstantiation() {
+    String json = "{\"street\":[\"123 W 14th St\",\"8th Fl\"],\"countryCode\":\"US\"}";
+    TestAddress address = GsonUtils.provideGson().fromJson(json, TestAddress.class);
+    assertThat(address.getStreet()).containsExactly("123 W 14th St", "8th Fl");
+    assertThat(address.getCountryCode()).isEqualTo("US");
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_tooManyStreetLines() {
+    String json = "{\"street\":[\"123 W 14th St\",\"8th Fl\",\"Rm 8\",\"4th Line\"]}";
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> GsonUtils.provideGson().fromJson(json, TestAddress.class));
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_emptyStreetLine() {
+    String json = "{\"street\":[\"123 W 14th St\",\"\"]}";
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> GsonUtils.provideGson().fromJson(json, TestAddress.class));
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_invalidCountryCode() {
+    String json = "{\"countryCode\":\"USA\"}";
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> GsonUtils.provideGson().fromJson(json, TestAddress.class));
+  }
+
   private static TestAddress createAddress(String... streetList) {
     return new TestAddress.Builder()
         .setStreet(ImmutableList.copyOf(streetList))

core/src/test/java/google/registry/model/registrar/RegistrarAddressTest.java

@@ -0,0 +1,94 @@
+// Copyright 2026 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.model.registrar;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import com.google.common.collect.ImmutableList;
+import google.registry.tools.GsonUtils;
+import org.junit.jupiter.api.Test;
+
+/** Unit tests for {@link RegistrarAddress}. */
+class RegistrarAddressTest {
+
+  @Test
+  void testSuccess_gsonInstantiation() {
+    String json = "{\"street\":[\"123 W 14th St\"],\"city\":\"New York\",\"countryCode\":\"US\"}";
+    RegistrarAddress address = GsonUtils.provideGson().fromJson(json, RegistrarAddress.class);
+    assertThat(address.getStreet()).containsExactly("123 W 14th St");
+    assertThat(address.getCity()).isEqualTo("New York");
+    assertThat(address.getCountryCode()).isEqualTo("US");
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_missingStreet() {
+    String json = "{\"city\":\"New York\",\"countryCode\":\"US\"}";
+    assertThrows(
+        NullPointerException.class,
+        () -> GsonUtils.provideGson().fromJson(json, RegistrarAddress.class));
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_missingCity() {
+    String json = "{\"street\":[\"123 W 14th St\"],\"countryCode\":\"US\"}";
+    assertThrows(
+        NullPointerException.class,
+        () -> GsonUtils.provideGson().fromJson(json, RegistrarAddress.class));
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_missingCountryCode() {
+    String json = "{\"street\":[\"123 W 14th St\"],\"city\":\"New York\"}";
+    assertThrows(
+        NullPointerException.class,
+        () -> GsonUtils.provideGson().fromJson(json, RegistrarAddress.class));
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_invalidCountryCode() {
+    String json = "{\"street\":[\"123 W 14th St\"],\"city\":\"New York\",\"countryCode\":\"USA\"}";
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> GsonUtils.provideGson().fromJson(json, RegistrarAddress.class));
+  }
+
+  @Test
+  void testFailure_gsonInstantiation_tooManyStreetLines() {
+    String json =
+        "{\"street\":[\"1\",\"2\",\"3\",\"4\"],\"city\":\"New York\",\"countryCode\":\"US\"}";
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> GsonUtils.provideGson().fromJson(json, RegistrarAddress.class));
+  }
+
+  @Test
+  void testSuccess_builder() {
+    RegistrarAddress address =
+        new RegistrarAddress.Builder()
+            .setStreet(ImmutableList.of("123 W 14th St"))
+            .setCity("New York")
+            .setCountryCode("US")
+            .build();
+    assertThat(address.getStreet()).containsExactly("123 W 14th St");
+  }
+
+  @Test
+  void testFailure_builder_missingStreet() {
+    assertThrows(
+        NullPointerException.class,
+        () -> new RegistrarAddress.Builder().setCity("New York").setCountryCode("US").build());
+  }
+}