**Build scan:**
https://gradle-enterprise.elastic.co/s/zy3maqdnytk64/tests/:server:test/org.elasticsearch.action.admin.indices.diskusage.TransportAnalyzeIndexDiskUsageActionTests/testRandomLimitConcurrentRequests

**Reproduction line:**
`./gradlew ':server:test' --tests "org.elasticsearch.action.admin.indices.diskusage.TransportAnalyzeIndexDiskUsageActionTests.testRandomLimitConcurrentRequests" -Dtests.seed=38580122459C0704 -Dtests.locale=mt -Dtests.timezone=Asia/Shanghai -Druntime.java=19`

**Applicable branches:**
8.3

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.action.admin.indices.diskusage.TransportAnalyzeIndexDiskUsageActionTests&tests.test=testRandomLimitConcurrentRequests

**Failure excerpt:**
```
java.lang.NullPointerException: Cannot invoke "org.elasticsearch.action.admin.indices.diskusage.IndexDiskUsageStats.getIndexSizeInBytes()" because the return value of "java.util.Map.get(Object)" is null

  at __randomizedtesting.SeedInfo.seed([38580122459C0704:1B67A99AA2E7C41C]:0)
  at org.elasticsearch.action.admin.indices.diskusage.TransportAnalyzeIndexDiskUsageActionTests.testRandomLimitConcurrentRequests(TransportAnalyzeIndexDiskUsageActionTests.java:211)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
  at java.lang.reflect.Method.invoke(Method.java:578)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:44)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:824)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:475)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:831)
  at java.lang.Thread.run(Thread.java:1596)

```
server/src/test/java/org/elasticsearch/action/admin/indices/diskusage/TransportAnalyzeIndexDiskUsageActionTests.java
pendingRequests.remove(r);
                if (nodeToShards.get(r.node).poll() != null) {
                    expectedRequestCounts.compute(r.node, (k, v) -> v == null ? 1 : v + 1);
                }
            }
            assertBusy(() -> assertThat(transportService.getRequestsSentPerNode(), equalTo(expectedRequestCounts)));
            pendingRequests.addAll(transportService.getCapturedRequests(true));
        }
        assertBusy(future::isDone);
        AnalyzeIndexDiskUsageResponse response = future.actionGet();
        assertThat(response.getTotalShards(), equalTo(numberOfShards));
        assertThat(response.getFailedShards(), equalTo(0));
        assertThat(response.getSuccessfulShards(), equalTo(numberOfShards));
        assertThat(response.getStats().get("test_index").getIndexSizeInBytes(), equalTo(totalIndexSizeInBytes.get()));
    }
    public void testRandomLimitConcurrentRequests() throws Exception {
        DiscoveryNodes nodes = newNodes(between(1, 20));
        int numberOfShards = randomIntBetween(1, 1000);
        Map<ShardId, List<ShardRouting>> shardToRoutings = new HashMap<>();
        for (int i = 0; i < numberOfShards; i++) {
            ShardId shardId = new ShardId("test_index", "n/a", i);
            List<ShardRouting> shardRoutings = randomSubsetOf(between(1, nodes.size()), nodes).stream()
                .map(node -> TestShardRouting.newShardRouting(shardId, node.getId(), randomBoolean(), ShardRoutingState.STARTED))
                .toList();
            shardToRoutings.put(shardId, shardRoutings);
        }
        Set<ShardId> failedShards = new HashSet<>(randomSubsetOf(between(0, (numberOfShards + 4) / 5), shardToRoutings.keySet()));
        int maxConcurrentRequests = randomIntBetween(1, 16);
        PlainActionFuture<AnalyzeIndexDiskUsageResponse> requestFuture = new PlainActionFuture<>();
        Queue<CapturingRequest> pendingRequests = ConcurrentCollections.newQueue();