operator-framework
diff --git a/.../test/java/io/javaoperatorsdk/operator/dependent/externalstate/ExternalStateTestBase.java b/.../test/java/io/javaoperatorsdk/operator/dependent/externalstate/ExternalStateTestBase.java
@@ -16,16 +16,19 @@
 package io.javaoperatorsdk.operator.dependent.externalstate;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 
 import io.fabric8.kubernetes.api.model.ConfigMap;
 import io.fabric8.kubernetes.api.model.ObjectMetaBuilder;
 import io.javaoperatorsdk.operator.junit.LocallyRunOperatorExtension;
 import io.javaoperatorsdk.operator.support.ExternalIDGenServiceMock;
+import io.javaoperatorsdk.operator.support.ExternalServiceResetExtension;
 
 import static io.javaoperatorsdk.operator.dependent.externalstate.ExternalStateReconciler.ID_KEY;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.awaitility.Awaitility.await;
 
+@ExtendWith(ExternalServiceResetExtension.class)
 public abstract class ExternalStateTestBase {
 
   private static final String TEST_RESOURCE_NAME = "test1";

diff --git a/...rsdk/operator/dependent/externalstate/externalstatebulkdependent/ExternalStateBulkIT.java b/...rsdk/operator/dependent/externalstate/externalstatebulkdependent/ExternalStateBulkIT.java
@@ -18,12 +18,14 @@
 import java.time.Duration;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.api.extension.RegisterExtension;
 
 import io.fabric8.kubernetes.api.model.ObjectMetaBuilder;
 import io.javaoperatorsdk.annotation.Sample;
 import io.javaoperatorsdk.operator.junit.LocallyRunOperatorExtension;
 import io.javaoperatorsdk.operator.support.ExternalIDGenServiceMock;
+import io.javaoperatorsdk.operator.support.ExternalServiceResetExtension;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.awaitility.Awaitility.await;
@@ -37,6 +39,7 @@
         allowing operators to track and reconcile a variable number of external resources with \
         persistent state that survives operator restarts.
         """)
+@ExtendWith(ExternalServiceResetExtension.class)
 class ExternalStateBulkIT {
 
   private static final String TEST_RESOURCE_NAME = "test1";

diff --git a/...framework/src/test/java/io/javaoperatorsdk/operator/support/ExternalIDGenServiceMock.java b/...framework/src/test/java/io/javaoperatorsdk/operator/support/ExternalIDGenServiceMock.java
@@ -50,6 +50,14 @@ public List<ExternalResource> listResources() {
     return new ArrayList<>(resourceMap.values());
   }
 
+  /**
+   * Clears the internal state. Intended to be called between tests so that state from one test does
+   * not leak into the next via this JVM-lifetime singleton.
+   */
+  public void reset() {
+    resourceMap.clear();
+  }
+
   public static ExternalIDGenServiceMock getInstance() {
     return serviceMock;
   }

diff --git a/...work/src/test/java/io/javaoperatorsdk/operator/support/ExternalServiceResetExtension.java b/...work/src/test/java/io/javaoperatorsdk/operator/support/ExternalServiceResetExtension.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright Java Operator SDK Authors
+ *
+ * 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 io.javaoperatorsdk.operator.support;
+
+import org.jspecify.annotations.NonNull;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+
+/**
+ * Resets the {@link ExternalIDGenServiceMock} singleton before each test method so that state from
+ * one test does not leak into the next. Apply via
+ * {@code @ExtendWith(ExternalServiceResetExtension.class)}.
+ */
+public class ExternalServiceResetExtension implements BeforeEachCallback {
+
+  @Override
+  public void beforeEach(@NonNull ExtensionContext context) {
+    ExternalIDGenServiceMock.getInstance().reset();
+  }
+}