KAFKA-19071: Fix doc for remote.storage.enable (#19345)

As of 3.9, Kafka allows disabling remote storage on a topic after it was
enabled. It allows subsequent enabling and disabling too.

However the documentation says otherwise and needs to be corrected.

Doc:
https://kafka.apache.org/39/documentation/#topicconfigs_remote.storage.enable

Reviewers: Luke Chen <showuon@gmail.com>, PoAn Yang <payang@apache.org>, Ken Huang <s7133700@gmail.com>

clients/src/main/java/org/apache/kafka/common/config/TopicConfig.java

@@ -80,8 +80,9 @@ public class TopicConfig {
         "Moreover, it triggers the rolling of new segment if the retention.ms condition is satisfied.";
 
     public static final String REMOTE_LOG_STORAGE_ENABLE_CONFIG = "remote.storage.enable";
-    public static final String REMOTE_LOG_STORAGE_ENABLE_DOC = "To enable tiered storage for a topic, set this configuration as true. " +
+    public static final String REMOTE_LOG_STORAGE_ENABLE_DOC = "To enable tiered storage for a topic, set this configuration to true. " +
-            "You can not disable this config once it is enabled. It will be provided in future versions.";
+            "To disable tiered storage for a topic that has it enabled, set this configuration to false. " +
+            "When disabling, you must also set <code>remote.log.delete.on.disable</code> to true.";
 
     public static final String LOCAL_LOG_RETENTION_MS_CONFIG = "local.retention.ms";
     public static final String LOCAL_LOG_RETENTION_MS_DOC = "The number of milliseconds to keep the local log segment before it gets deleted. " +

core/src/test/scala/integration/kafka/admin/RemoteTopicCrudTest.scala

@@ -441,7 +441,36 @@ class RemoteTopicCrudTest extends IntegrationTestHarness {
           AlterConfigOp.OpType.SET),
       ))
     assertThrowsException(classOf[InvalidConfigurationException],
-      () => admin.incrementalAlterConfigs(configs).all().get(), "Disabling remote storage feature on the topic level is not supported.")
+      () => admin.incrementalAlterConfigs(configs).all().get(), "It is invalid to disable remote storage without deleting remote data. " +
+        "If you want to keep the remote data and turn to read only, please set `remote.storage.enable=true,remote.log.copy.disable=true`. " +
+        "If you want to disable remote storage and delete all remote data, please set `remote.storage.enable=false,remote.log.delete.on.disable=true`.")
+  }
+
+  @ParameterizedTest
+  @ValueSource(strings = Array("kraft"))
+  def testUpdateTopicConfigWithDisablingRemoteStorageWithDeleteOnDisable(quorum: String): Unit = {
+    val admin = createAdminClient()
+    val topicConfig = new Properties
+    topicConfig.setProperty(TopicConfig.REMOTE_LOG_STORAGE_ENABLE_CONFIG, "true")
+    TestUtils.createTopicWithAdmin(admin, testTopicName, brokers, controllerServers, numPartitions, numReplicationFactor,
+      topicConfig = topicConfig)
+
+    val configs = new util.HashMap[ConfigResource, util.Collection[AlterConfigOp]]()
+    configs.put(new ConfigResource(ConfigResource.Type.TOPIC, testTopicName),
+      util.Arrays.asList(
+        new AlterConfigOp(new ConfigEntry(TopicConfig.REMOTE_LOG_STORAGE_ENABLE_CONFIG, "false"),
+          AlterConfigOp.OpType.SET),
+        new AlterConfigOp(new ConfigEntry(TopicConfig.REMOTE_LOG_DELETE_ON_DISABLE_CONFIG, "true"),
+          AlterConfigOp.OpType.SET)
+      ))
+    admin.incrementalAlterConfigs(configs).all().get()
+
+    val newProps = new Properties()
+    configs.get(new ConfigResource(ConfigResource.Type.TOPIC, testTopicName)).forEach { op =>
+      newProps.setProperty(op.configEntry().name(), op.configEntry().value())
+    }
+
+    verifyRemoteLogTopicConfigs(newProps)
   }
 
   @ParameterizedTest