diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleAction.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleAction.java
index 28d15c87db8..531036daa99 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleAction.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleAction.java
@@ -57,14 +57,6 @@ public class DeleteLifecycleAction
             super(acknowledged);
         }
 
-        @Override
-        public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-            builder.startObject();
-            addAcknowledgedField(builder);
-            builder.endObject();
-            return builder;
-        }
-
         @Override
         public void readFrom(StreamInput in) throws IOException {
             readAcknowledged(in);
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleAction.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleAction.java
index 88a1a4c223c..a813c332c89 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleAction.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleAction.java
@@ -59,14 +59,6 @@ public class PutLifecycleAction extends Action<PutLifecycleAction.Request, PutLi
             super(acknowledged);
         }
 
-        @Override
-        public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-            builder.startObject();
-            addAcknowledgedField(builder);
-            builder.endObject();
-            return builder;
-        }
-
         @Override
         public void readFrom(StreamInput in) throws IOException {
             readAcknowledged(in);
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleRequestTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleRequestTests.java
index 82e008cd25f..38f36bb76dd 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleRequestTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleRequestTests.java
@@ -22,8 +22,8 @@ public class DeleteLifecycleRequestTests extends AbstractStreamableTestCase<Dele
     }
 
     @Override
-    protected MutateFunction<Request> getMutateFunction() {
-        return resp -> new Request(resp.getPolicyName() + randomAlphaOfLengthBetween(1, 10));
+    protected Request mutateInstance(Request request) {
+        return new Request(request.getPolicyName() + randomAlphaOfLengthBetween(1, 10));
     }
 
 }
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleResponseTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleResponseTests.java
index abff643f674..3467e48a813 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleResponseTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/DeleteLifecycleResponseTests.java
@@ -22,8 +22,8 @@ public class DeleteLifecycleResponseTests extends AbstractStreamableTestCase<Del
     }
 
     @Override
-    protected MutateFunction<Response> getMutateFunction() {
-        return resp -> new Response(resp.isAcknowledged() == false);
+    protected Response mutateInstance(Response response) {
+        return new Response(response.isAcknowledged() == false);
     }
 
 }
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleRequestTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleRequestTests.java
index 323e1b815f9..167f8138216 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleRequestTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleRequestTests.java
@@ -22,7 +22,7 @@ public class GetLifecycleRequestTests extends AbstractStreamableTestCase<GetLife
     }
 
     @Override
-    protected MutateFunction<Request> getMutateFunction() {
-        return resp -> new Request(resp.getPolicyName() + randomAlphaOfLengthBetween(1, 10));
+    protected Request mutateInstance(Request request) {
+        return new Request(request.getPolicyName() + randomAlphaOfLengthBetween(1, 10));
     }
 }
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleResponseTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleResponseTests.java
index 9683d55263d..92efcd210b2 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleResponseTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/GetLifecycleResponseTests.java
@@ -50,25 +50,23 @@ public class GetLifecycleResponseTests extends AbstractStreamableTestCase<GetLif
     }
 
     @Override
-    protected MutateFunction<Response> getMutateFunction() {
-        return resp -> {
-            LifecyclePolicy policy = resp.getPolicy();
-            String name = policy.getName();
-            Map<String, Phase> phases = policy.getPhases();
-            switch (between(0, 1)) {
-                case 0:
-                    name = name + randomAlphaOfLengthBetween(1, 5);
-                    break;
-                case 1:
-                    phases = new HashMap<>(phases);
-                    String newPhaseName = randomAlphaOfLengthBetween(1, 10);
-                    phases.put(name, new Phase(newPhaseName, TimeValue.timeValueSeconds(randomIntBetween(1, 1000)),
-                        Collections.emptyMap()));
-                    break;
-                default:
-                    throw new AssertionError("Illegal randomisation branch");
-            }
-            return new Response(new LifecyclePolicy(TestLifecycleType.INSTANCE, name, phases));
-        };
+    protected Response mutateInstance(Response response) {
+        LifecyclePolicy policy = response.getPolicy();
+        String name = policy.getName();
+        Map<String, Phase> phases = policy.getPhases();
+        switch (between(0, 1)) {
+            case 0:
+                name = name + randomAlphaOfLengthBetween(1, 5);
+                break;
+            case 1:
+                phases = new HashMap<>(phases);
+                String newPhaseName = randomAlphaOfLengthBetween(1, 10);
+                phases.put(name, new Phase(newPhaseName, TimeValue.timeValueSeconds(randomIntBetween(1, 1000)),
+                    Collections.emptyMap()));
+                break;
+            default:
+                throw new AssertionError("Illegal randomisation branch");
+        }
+        return new Response(new LifecyclePolicy(TestLifecycleType.INSTANCE, name, phases));
     }
 }
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleRequestTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleRequestTests.java
index 8bb0b5431c2..51087ff5af4 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleRequestTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleRequestTests.java
@@ -74,26 +74,24 @@ public class PutLifecycleRequestTests extends AbstractStreamableXContentTestCase
     }
 
     @Override
-    protected MutateFunction<Request> getMutateFunction() {
-        return resp -> {
-            LifecyclePolicy policy = resp.getPolicy();
-            String name = policy.getName();
-            Map<String, Phase> phases = policy.getPhases();
-            switch (between(0, 1)) {
-                case 0:
-                    name = name + randomAlphaOfLengthBetween(1, 5);
-                    break;
-                case 1:
-                    phases = new HashMap<>(phases);
-                    String newPhaseName = randomAlphaOfLengthBetween(1, 10);
-                    phases.put(name, new Phase(newPhaseName, TimeValue.timeValueSeconds(randomIntBetween(1, 1000)),
-                        Collections.emptyMap()));
-                    break;
-                default:
-                    throw new AssertionError("Illegal randomisation branch");
-            }
-            return new Request(new LifecyclePolicy(TestLifecycleType.INSTANCE, name, phases));
-        };
+    protected Request mutateInstance(Request request) {
+        LifecyclePolicy policy = request.getPolicy();
+        String name = policy.getName();
+        Map<String, Phase> phases = policy.getPhases();
+        switch (between(0, 1)) {
+            case 0:
+                name = name + randomAlphaOfLengthBetween(1, 5);
+                break;
+            case 1:
+                phases = new HashMap<>(phases);
+                String newPhaseName = randomAlphaOfLengthBetween(1, 10);
+                phases.put(name, new Phase(newPhaseName, TimeValue.timeValueSeconds(randomIntBetween(1, 1000)),
+                    Collections.emptyMap()));
+                break;
+            default:
+                throw new AssertionError("Illegal randomisation branch");
+        }
+        return new Request(new LifecyclePolicy(TestLifecycleType.INSTANCE, name, phases));
     }
 
 }
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleResponseTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleResponseTests.java
index e0dde842af9..c780bf5f5ed 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleResponseTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/indexlifecycle/action/PutLifecycleResponseTests.java
@@ -22,8 +22,8 @@ public class PutLifecycleResponseTests extends AbstractStreamableTestCase<PutLif
     }
 
     @Override
-    protected MutateFunction<Response> getMutateFunction() {
-        return resp -> new Response(resp.isAcknowledged() == false);
+    protected Response mutateInstance(Response response) {
+        return new Response(response.isAcknowledged() == false);
     }
 
 }