MINOR: regression in export field setter (#27447)

* fix: regression in export field setter

* fix: restore hydrateHistoryEntities hook after setFieldsInBulk and update javadoc

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Co-authored-by: TeddyCr <13626425+TeddyCr@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: TeddyCr <13626425+TeddyCr@users.noreply.github.com>

Author: TeddyCr

openmetadata-integration-tests/src/test/java/org/openmetadata/it/tests/DatabaseResourceIT.java

@@ -7,6 +7,8 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -35,13 +37,15 @@
 import org.openmetadata.schema.type.Column;
 import org.openmetadata.schema.type.ColumnDataType;
 import org.openmetadata.schema.type.EntityHistory;
+import org.openmetadata.schema.type.EntityReference;
 import org.openmetadata.schema.type.api.BulkOperationResult;
 import org.openmetadata.schema.type.csv.CsvImportResult;
 import org.openmetadata.sdk.client.OpenMetadataClient;
 import org.openmetadata.sdk.exceptions.InvalidRequestException;
 import org.openmetadata.sdk.fluent.Databases;
 import org.openmetadata.sdk.models.ListParams;
 import org.openmetadata.sdk.models.ListResponse;
+import org.openmetadata.sdk.network.HttpMethod;
 import org.openmetadata.service.util.FullyQualifiedName;
 
 /**
@@ -1702,4 +1706,47 @@ void testRegexListDatabase_excludeMode(TestNamespace ns) {
         databases.stream().noneMatch(d -> d.getName().startsWith("temp")),
         "Excluded databases should not appear in results");
   }
+
+  @Test
+  void test_listEntityHistoryByTimestamp_returnsServiceField(TestNamespace ns) throws Exception {
+    OpenMetadataClient client = SdkClients.adminClient();
+    long startTs = System.currentTimeMillis();
+
+    CreateDatabase createRequest = createRequest(ns.prefix("history_service_field"), ns);
+    Database database = createEntity(createRequest);
+
+    database.setDescription("Updated for history test - " + System.currentTimeMillis());
+    patchEntity(database.getId().toString(), database);
+
+    long endTs = System.currentTimeMillis();
+    String basePath = getResourcePath() + "history";
+
+    String response =
+        client
+            .getHttpClient()
+            .executeForString(
+                HttpMethod.GET,
+                basePath + "?startTs=" + startTs + "&endTs=" + endTs + "&limit=10",
+                null);
+
+    ObjectMapper mapper = new ObjectMapper();
+    JsonNode result = mapper.readTree(response);
+    JsonNode data = result.get("data");
+
+    assertTrue(data.isArray(), "Data should be an array");
+    assertTrue(data.size() > 0, "Should have at least one version in the time range");
+
+    for (JsonNode entityNode : data) {
+      assertTrue(
+          entityNode.has("service") && !entityNode.get("service").isNull(),
+          "Each database version must include the required 'service' field, but got: "
+              + entityNode);
+
+      Database deserialized = mapper.treeToValue(entityNode, Database.class);
+      EntityReference service = deserialized.getService();
+      assertNotNull(service, "Deserialized database must have a non-null service reference");
+      assertNotNull(service.getId(), "Service reference must have an id");
+      assertNotNull(service.getType(), "Service reference must have a type");
+    }
+  }
 }

openmetadata-service/src/main/java/org/openmetadata/service/jdbi3/EntityRepository.java

@@ -2287,6 +2287,7 @@ public final ResultList<T> listEntityHistoryByTimestamp(
                 fetchLimit);
 
     List<T> entities = JsonUtils.readObjects(jsons, getEntityClass());
+    setFieldsInBulk(putFields, entities);
     hydrateHistoryEntities(entities);
 
     int total = getVersionCountCached(tableName, startTs, endTs, entityType);
@@ -2325,14 +2326,14 @@ public final ResultList<T> listEntityHistoryByTimestamp(
   }
 
   /**
-   * Hook to hydrate entities returned from {@link #listEntityHistoryByTimestamp(long, long, String,
-   * String, int)}.
+   * Hook called after {@link #setFieldsInBulk} for entities returned from {@link
+   * #listEntityHistoryByTimestamp(long, long, String, String, int)}.
    *
-   * <p>Default behavior is intentionally lightweight: return the historical snapshots as stored in
-   * the extension table and avoid expensive relationship re-hydration for each row.
+   * <p>Subclasses may override to perform additional, entity-specific hydration of history
+   * snapshots without overriding the core field-population logic in {@code setFieldsInBulk}.
    */
   protected void hydrateHistoryEntities(List<T> entities) {
-    // Historical snapshots are already serialized versions; avoid N+1 hydration on /history.
+    // No additional hydration by default.
   }
 
   private String decodeAndValidateCursor(String cursor) {