Fix NPE in HealthApiFeatureSetUsageTests testEqualsAndHashcode

Author: cbuescher

muted-tests.yml

@@ -579,9 +579,6 @@ tests:
 - class: org.elasticsearch.xpack.remotecluster.CrossClusterEsqlRCS2UnavailableRemotesIT
   method: testEsqlRcs2UnavailableRemoteScenarios
   issue: https://github.com/elastic/elasticsearch/issues/136493
-- class: org.elasticsearch.xpack.core.HealthApiFeatureSetUsageTests
-  method: testEqualsAndHashcode
-  issue: https://github.com/elastic/elasticsearch/issues/136648
 - class: org.elasticsearch.xpack.downsample.ILMDownsampleDisruptionIT
   method: testILMDownsampleRollingRestart
   issue: https://github.com/elastic/elasticsearch/issues/136585

test/framework/src/main/java/org/elasticsearch/test/AbstractWireTestCase.java

@@ -54,7 +54,7 @@ public abstract class AbstractWireTestCase<T> extends ESTestCase {
      * Tests that the equals and hashcode methods are consistent and copied
      * versions of the instance are equal.
      */
-    public final void testEqualsAndHashcode() {
+    public void testEqualsAndHashcode() {
         for (int runs = 0; runs < NUMBER_OF_TEST_RUNS; runs++) {
             T testInstance = createTestInstance();
             try {

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/HealthApiFeatureSetUsageTests.java

@@ -27,6 +27,8 @@
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.notNullValue;
 
+
+
 public class HealthApiFeatureSetUsageTests extends AbstractWireSerializingTestCase<HealthApiFeatureSetUsage> {
 
     @Override
@@ -37,9 +39,9 @@ protected HealthApiFeatureSetUsage createTestInstance() {
     @Override
     protected HealthApiFeatureSetUsage mutateInstance(HealthApiFeatureSetUsage instance) {
         Map<String, Object> originalStats = instance.stats();
-        Counters newStats = randomCounters();
+        Counters newStats = randomCounters(false);
         while (originalStats.equals(newStats.toMutableNestedMap())) {
-            newStats = randomCounters();
+            newStats = randomCounters(false);
         }
         return new HealthApiFeatureSetUsage(true, true, newStats);
     }
@@ -50,7 +52,11 @@ protected Writeable.Reader<HealthApiFeatureSetUsage> instanceReader() {
     }
 
     private Counters randomCounters() {
-        if (rarely()) {
+        return randomCounters(true);
+    }
+
+    private Counters randomCounters(boolean allowNull) {
+        if (allowNull && rarely()) {
             return null;
         }
         Counters counters = new Counters();