[FSTORE-1912] java client-fix for 400 error code change for feature group not found

java/hsfs/src/main/java/com/logicalclocks/hsfs/engine/FeatureGroupEngine.java

@@ -99,7 +99,7 @@ public StreamFeatureGroup getOrCreateFeatureGroup(FeatureStore featureStore, @No
     try {
       return getStreamFeatureGroup(featureStore, name, version);
     } catch (IOException | FeatureStoreException e) {
-      if (e.getMessage().contains("Error: 404") && e.getMessage().contains("\"errorCode\":270009")) {
+      if (e.getMessage().contains("\"errorCode\":270009")) {
         return StreamFeatureGroup.builder()
             .featureStore(featureStore)
             .name(name)

java/hsfs/src/test/java/com/logicalclocks/hsfs/engine/TestFeatureGroupEngine.java

@@ -0,0 +1,105 @@
+/*
+ *  Copyright (c) 2026. Hopsworks AB
+ *
+ *  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.logicalclocks.hsfs.engine;
+
+import com.logicalclocks.hsfs.FeatureStore;
+import com.logicalclocks.hsfs.StreamFeatureGroup;
+import com.logicalclocks.hsfs.TimeTravelFormat;
+import com.logicalclocks.hsfs.metadata.FeatureGroupApi;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.Collections;
+
+class TestFeatureGroupEngine {
+
+  private FeatureGroupEngine engine;
+  private FeatureGroupApi mockApi;
+  private FeatureStore mockFeatureStore;
+
+  @BeforeEach
+  void setUp() throws Exception {
+    engine = new FeatureGroupEngine();
+    mockApi = Mockito.mock(FeatureGroupApi.class);
+    mockFeatureStore = Mockito.mock(FeatureStore.class);
+
+    Field apiField = FeatureGroupEngineBase.class.getDeclaredField("featureGroupApi");
+    apiField.setAccessible(true);
+    apiField.set(engine, mockApi);
+  }
+
+  @Test
+  void testGetOrCreateReturnsFgWhenBackendReturns400NotFound() throws Exception {
+    // Backend returns 400 with errorCode 270009 (feature group not found)
+    Mockito.when(mockApi.getInternal(Mockito.any(), Mockito.any(), Mockito.any(), Mockito.any()))
+        .thenThrow(new IOException("Error: 400{\"errorCode\":270009,\"errorMsg\":\"Featuregroup wasn't found.\"}"));
+
+    StreamFeatureGroup result = engine.getOrCreateFeatureGroup(
+        mockFeatureStore, "test_fg", 1, "desc", true,
+        TimeTravelFormat.HUDI, Collections.singletonList("id"),
+        Collections.emptyList(), null, "id", Collections.emptyList(),
+        null, null, null, null);
+
+    Assert.assertNotNull(result);
+    Assert.assertEquals("test_fg", result.getName());
+    Assert.assertEquals(Integer.valueOf(1), result.getVersion());
+    Assert.assertEquals(true, result.getOnlineEnabled());
+  }
+
+  @Test
+  void testGetStreamFeatureGroupReturnsExistingFg() throws Exception {
+    // Backend returns an existing feature group
+    StreamFeatureGroup existing = new StreamFeatureGroup();
+    existing.setName("existing_fg");
+    existing.setVersion(1);
+    Mockito.when(mockApi.getInternal(Mockito.any(), Mockito.any(), Mockito.any(), Mockito.any()))
+        .thenReturn(new StreamFeatureGroup[]{existing});
+
+    StreamFeatureGroup result = engine.getStreamFeatureGroup(mockFeatureStore, "existing_fg", 1);
+
+    Assert.assertNotNull(result);
+    Assert.assertEquals("existing_fg", result.getName());
+    Assert.assertEquals(Integer.valueOf(1), result.getVersion());
+  }
+
+  @Test
+  void testGetOrCreateRethrowsUnrelatedExceptions() {
+    // Errors unrelated to "not found" should propagate
+    try {
+      Mockito.when(mockApi.getInternal(Mockito.any(), Mockito.any(), Mockito.any(), Mockito.any()))
+          .thenThrow(new IOException("Error: 500{\"errorCode\":500000,\"errorMsg\":\"Internal server error.\"}"));
+
+      engine.getOrCreateFeatureGroup(
+          mockFeatureStore, "test_fg", 1, "desc", true,
+          TimeTravelFormat.HUDI, Collections.singletonList("id"),
+          Collections.emptyList(), null, "id", Collections.emptyList(),
+          null, null, null, null);
+
+      Assert.fail("Expected IOException to be rethrown");
+    } catch (IOException | com.logicalclocks.hsfs.FeatureStoreException e) {
+      Assert.assertTrue(e.getMessage().contains("500000"));
+    } catch (Exception e) {
+      Assert.fail("Unexpected exception type: " + e.getClass());
+    }
+  }
+}