fix(breaking): remove "DisplayName" from Owner

This is a breaking change, S3Mock will not be able to read from existing
file systems created with older versions.
Pretty confusing - "DisplayName" is used all over the place in
AWS, but for some reason, it's only removed from the "Owner"
data structure.
There is no documentation, blog post, etc to be found, just emails sent
to account owners. The API for "Owner" still lists "DisplayName", with
no deprecation notice.
The SDKs also do not contain a deprecation notice.

Fixes #2738

Author: afranken

integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/AclIT.kt

@@ -63,7 +63,6 @@ internal class AclIT : S3TestBase() {
       }.also { resp ->
         assertThat(resp.sdkHttpResponse().isSuccessful).isTrue()
         assertThat(resp.owner().id()).isNotBlank()
-        assertThat(resp.owner().displayName()).isNotBlank()
         assertThat(resp.grants()).hasSize(1)
         assertThat(resp.grants().first().permission()).isEqualTo(FULL_CONTROL)
       }
@@ -86,7 +85,6 @@ internal class AclIT : S3TestBase() {
 
     acl.owner().also { owner ->
       assertThat(owner.id()).isEqualTo(DEFAULT_OWNER.id)
-      assertThat(owner.displayName()).isEqualTo(DEFAULT_OWNER.displayName)
     }
 
     acl.grants().also {
@@ -102,7 +100,6 @@ internal class AclIT : S3TestBase() {
       .also { grantee ->
         assertThat(grantee).isNotNull
         assertThat(grantee.id()).isEqualTo(DEFAULT_OWNER.id)
-        assertThat(grantee.displayName()).isEqualTo(DEFAULT_OWNER.displayName)
         assertThat(grantee.type()).isEqualTo(CANONICAL_USER)
       }
   }
@@ -126,7 +123,6 @@ internal class AclIT : S3TestBase() {
       it.accessControlPolicy {
         it.owner {
           it.id(userId)
-          it.displayName(userName)
         }
         it
           .grants(
@@ -150,7 +146,6 @@ internal class AclIT : S3TestBase() {
     acl.owner().also {
       assertThat(it).isNotNull
       assertThat(it.id()).isEqualTo(userId)
-      assertThat(it.displayName()).isEqualTo(userName)
     }
 
     assertThat(acl.grants()).hasSize(1)

integration-tests/src/test/kotlin/com/adobe/testing/s3mock/its/BucketIT.kt

@@ -167,7 +167,6 @@ internal class BucketIT : S3TestBase() {
       }
       assertThat(it.prefix()).isNull()
       assertThat(it.continuationToken()).isNull()
-      assertThat(it.owner().displayName()).isEqualTo("s3-mock-file-store")
       assertThat(it.owner().id()).isEqualTo("79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
     }
   }
@@ -205,7 +204,6 @@ internal class BucketIT : S3TestBase() {
         }
         assertThat(it.prefix()).isEqualTo(bucketName)
         assertThat(it.continuationToken()).isNull()
-        assertThat(it.owner().displayName()).isEqualTo("s3-mock-file-store")
         assertThat(it.owner().id()).isEqualTo("79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
       }
   }
@@ -245,7 +243,6 @@ internal class BucketIT : S3TestBase() {
           }
           assertThat(it.prefix()).isNull()
           assertThat(it.continuationToken()).isNotNull
-          assertThat(it.owner().displayName()).isEqualTo("s3-mock-file-store")
           assertThat(it.owner().id()).isEqualTo("79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
         }.continuationToken()
 
@@ -263,7 +260,6 @@ internal class BucketIT : S3TestBase() {
         }
         assertThat(it.prefix()).isNull()
         assertThat(it.continuationToken()).isNull()
-        assertThat(it.owner().displayName()).isEqualTo("s3-mock-file-store")
         assertThat(it.owner().id()).isEqualTo("79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
       }
   }

server/src/main/kotlin/com/adobe/testing/s3mock/controller/MultipartController.kt

@@ -23,6 +23,7 @@ import com.adobe.testing.s3mock.dto.CompleteMultipartUploadResult
 import com.adobe.testing.s3mock.dto.CopyPartResult
 import com.adobe.testing.s3mock.dto.CopySource
 import com.adobe.testing.s3mock.dto.InitiateMultipartUploadResult
+import com.adobe.testing.s3mock.dto.Initiator
 import com.adobe.testing.s3mock.dto.ListMultipartUploadsResult
 import com.adobe.testing.s3mock.dto.ListPartsResult
 import com.adobe.testing.s3mock.dto.ObjectKey
@@ -382,7 +383,7 @@ class MultipartController(
         contentType,
         storeHeadersFrom(httpHeaders),
         Owner.DEFAULT_OWNER,
-        Owner.DEFAULT_OWNER,
+        Initiator.DEFAULT_INITIATOR,
         userMetadataFrom(httpHeaders),
         encryptionHeaders,
         tags,

server/src/main/kotlin/com/adobe/testing/s3mock/dto/Initiator.kt

@@ -0,0 +1,35 @@
+/*
+ *  Copyright 2017-2025 Adobe.
+ *
+ *  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 com.adobe.testing.s3mock.dto
+
+import com.adobe.testing.S3Verified
+import com.fasterxml.jackson.annotation.JsonProperty
+
+/**
+ * [API Reference](https://docs.aws.amazon.com/AmazonS3/latest/API/API_Initiator.html).
+ */
+@S3Verified(year = 2025)
+data class Initiator(
+  @param:JsonProperty("DisplayName", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
+  val displayName: String?,
+  @param:JsonProperty("ID", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
+  val id: String?
+) {
+  companion object {
+    val DEFAULT_INITIATOR: Initiator =
+      Initiator("s3-mock-file-store", "79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
+  }
+}

server/src/main/kotlin/com/adobe/testing/s3mock/dto/ListPartsResult.kt

@@ -34,7 +34,7 @@ data class ListPartsResult(
   @param:JsonProperty("ChecksumType", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
   val checksumType: ChecksumType?,
   @param:JsonProperty("Initiator", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
-  val initiator: Owner?,
+  val initiator: Initiator?,
   @param:JsonProperty("IsTruncated", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
   val isTruncated: Boolean,
   @param:JsonProperty("Key", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")

server/src/main/kotlin/com/adobe/testing/s3mock/dto/MultipartUpload.kt

@@ -34,7 +34,7 @@ data class MultipartUpload(
   @param:JsonProperty("Initiated", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
   val initiated: Date?,
   @param:JsonProperty("Initiator", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
-  val initiator: Owner?,
+  val initiator: Initiator?,
   @param:JsonProperty("Key", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
   val key: String,
   @param:JsonProperty("Owner", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")

server/src/main/kotlin/com/adobe/testing/s3mock/dto/Owner.kt

@@ -24,19 +24,14 @@ import com.fasterxml.jackson.annotation.JsonProperty
  */
 @S3Verified(year = 2025)
 data class Owner(
-  @Deprecated("AWS deprecated this field in 2025-05")
-  @param:JsonProperty("DisplayName", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
-  val displayName: String? = null,
   @param:JsonProperty("ID", namespace = "http://s3.amazonaws.com/doc/2006-03-01/")
   val id: String?
 ) {
   companion object {
     /**
      * Default owner in S3Mock until support for ownership is implemented.
      */
-    val DEFAULT_OWNER: Owner =
-      Owner("s3-mock-file-store", "79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
-    val DEFAULT_OWNER_BUCKET: Owner =
-      Owner("s3-mock-file-store-bucket", "79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2df")
+    val DEFAULT_OWNER: Owner = Owner("79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be")
+    val DEFAULT_OWNER_BUCKET: Owner = Owner("79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2df")
   }
 }

server/src/main/kotlin/com/adobe/testing/s3mock/service/MultipartService.kt

@@ -22,6 +22,7 @@ import com.adobe.testing.s3mock.dto.CompleteMultipartUploadResult
 import com.adobe.testing.s3mock.dto.CompletedPart
 import com.adobe.testing.s3mock.dto.CopyPartResult
 import com.adobe.testing.s3mock.dto.InitiateMultipartUploadResult
+import com.adobe.testing.s3mock.dto.Initiator
 import com.adobe.testing.s3mock.dto.ListMultipartUploadsResult
 import com.adobe.testing.s3mock.dto.ListPartsResult
 import com.adobe.testing.s3mock.dto.MultipartUpload
@@ -189,7 +190,7 @@ open class MultipartService(private val bucketStore: BucketStore, private val mu
     contentType: String?,
     storeHeaders: Map<String, String>,
     owner: Owner,
-    initiator: Owner,
+    initiator: Initiator,
     userMetadata: Map<String, String>,
     encryptionHeaders: Map<String, String>,
     tags: List<Tag>?,

server/src/main/kotlin/com/adobe/testing/s3mock/store/MultipartStore.kt

@@ -21,6 +21,7 @@ import com.adobe.testing.s3mock.dto.ChecksumAlgorithm
 import com.adobe.testing.s3mock.dto.ChecksumType
 import com.adobe.testing.s3mock.dto.CompleteMultipartUploadResult
 import com.adobe.testing.s3mock.dto.CompletedPart
+import com.adobe.testing.s3mock.dto.Initiator
 import com.adobe.testing.s3mock.dto.MultipartUpload
 import com.adobe.testing.s3mock.dto.Owner
 import com.adobe.testing.s3mock.dto.Part
@@ -64,7 +65,7 @@ open class MultipartStore(private val objectStore: ObjectStore, private val obje
     contentType: String?,
     storeHeaders: Map<String, String>,
     owner: Owner,
-    initiator: Owner,
+    initiator: Initiator,
     userMetadata: Map<String, String>,
     encryptionHeaders: Map<String, String>,
     tags: List<Tag>?,

server/src/main/kotlin/com/adobe/testing/s3mock/store/ObjectStore.kt

@@ -121,7 +121,7 @@ open class ObjectStore(
 
   private fun privateCannedAcl(owner: Owner): AccessControlPolicy {
     val grant = Grant(
-      CanonicalUser(owner.displayName, owner.id),
+      CanonicalUser(null, owner.id),
       Grant.Permission.FULL_CONTROL
     )
     return AccessControlPolicy(listOf(grant), owner)