diff --git a/src/main/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventLocks.java b/src/main/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventLocks.java
index bbff4ee..a0d344b 100644
--- a/src/main/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventLocks.java
+++ b/src/main/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventLocks.java
@@ -23,6 +23,7 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
 
 public class IndexEventLocks {
   private static final FluentLogger log = FluentLogger.forEnclosingClass();
@@ -39,15 +40,15 @@
   }
 
   public CompletableFuture<?> withLock(
-      IndexTask id, IndexCallFunction function, VoidFunction lockAcquireTimeoutCallback) {
+      IndexTask id, Supplier<CompletableFuture<?>> indexTask, Runnable lockAcquireTimeoutCallback) {
     String indexId = id.indexId();
     Semaphore idSemaphore = getSemaphore(indexId);
     try {
       log.atFine().log("Trying to acquire %s", id);
       if (idSemaphore.tryAcquire(WAIT_TIMEOUT_MS, TimeUnit.MILLISECONDS)) {
         log.atFine().log("Acquired %s", id);
-        return function
-            .invoke()
+        return indexTask
+            .get()
             .whenComplete(
                 (result, error) -> {
                   try {
@@ -66,7 +67,7 @@
               "Acquisition of the locking of %s timed out after %d msec: consider increasing the number of shards",
               indexId, WAIT_TIMEOUT_MS);
       log.atWarning().log("%s", timeoutMessage);
-      lockAcquireTimeoutCallback.invoke();
+      lockAcquireTimeoutCallback.run();
       CompletableFuture<?> failureFuture = new CompletableFuture<>();
       failureFuture.completeExceptionally(new InterruptedException(timeoutMessage));
       return failureFuture;
@@ -82,14 +83,4 @@
   protected Semaphore getSemaphore(String indexId) {
     return semaphores.get(indexId);
   }
-
-  @FunctionalInterface
-  public interface VoidFunction {
-    void invoke();
-  }
-
-  @FunctionalInterface
-  public interface IndexCallFunction {
-    CompletableFuture<?> invoke();
-  }
 }
diff --git a/src/test/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventHandlerTest.java b/src/test/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventHandlerTest.java
index 7c6a4f6..bf87e4d 100644
--- a/src/test/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventHandlerTest.java
+++ b/src/test/java/com/ericsson/gerrit/plugins/highavailability/index/IndexEventHandlerTest.java
@@ -34,7 +34,6 @@
 import com.ericsson.gerrit.plugins.highavailability.index.IndexEventHandler.IndexChangeTask;
 import com.ericsson.gerrit.plugins.highavailability.index.IndexEventHandler.IndexGroupTask;
 import com.ericsson.gerrit.plugins.highavailability.index.IndexEventHandler.IndexTask;
-import com.ericsson.gerrit.plugins.highavailability.index.IndexEventLocks.VoidFunction;
 import com.google.gerrit.entities.Account;
 import com.google.gerrit.entities.AccountGroup;
 import com.google.gerrit.entities.Change;
@@ -567,14 +566,11 @@
     private IndexTask task;
     private CyclicBarrier testBarrier;
     private Supplier<T> successFunc;
-    private VoidFunction failureFunc;
+    private Runnable failureFunc;
     private CompletableFuture<T> future;
 
     public TestTask(
-        IndexTask task,
-        CyclicBarrier testBarrier,
-        Supplier<T> successFunc,
-        VoidFunction failureFunc) {
+        IndexTask task, CyclicBarrier testBarrier, Supplier<T> successFunc, Runnable failureFunc) {
       this.task = task;
       this.testBarrier = testBarrier;
       this.successFunc = successFunc;
@@ -598,7 +594,7 @@
                         }),
                 () -> {
                   await();
-                  failureFunc.invoke();
+                  failureFunc.run();
                 })
             .whenComplete(
                 (v, t) -> {