Minor simplification to get-snapshots action (#110959)

Inlines some methods that are now only used in one place.

server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/get/TransportGetSnapshotsAction.java

@@ -255,7 +255,15 @@ public class TransportGetSnapshotsAction extends TransportMasterNodeAction<GetSn
                             }
 
                             SubscribableListener.<RepositoryData>newForked(l -> maybeGetRepositoryData(repoName, l))
-                                .<Void>andThen((l, repositoryData) -> loadSnapshotInfos(repoName, repositoryData, l))
+                                .<Void>andThen((repositoryListener, repositoryData) -> {
+                                    assert ThreadPool.assertCurrentThreadPool(ThreadPool.Names.MANAGEMENT);
+                                    cancellableTask.ensureNotCancelled();
+                                    ensureRequiredNamesPresent(repoName, repositoryData);
+                                    loadSnapshotInfos(
+                                        getAsyncSnapshotInfoIterator(repositoriesService.repository(repoName), repositoryData),
+                                        repositoryListener
+                                    );
+                                })
                                 .addListener(listeners.acquire());
                         }
                     }
@@ -281,14 +289,6 @@ public class TransportGetSnapshotsAction extends TransportMasterNodeAction<GetSn
             }
         }
 
-        private void loadSnapshotInfos(String repositoryName, @Nullable RepositoryData repositoryData, ActionListener<Void> listener) {
-            assert ThreadPool.assertCurrentThreadPool(ThreadPool.Names.MANAGEMENT);
-            cancellableTask.ensureNotCancelled();
-            final var repository = repositoriesService.repository(repositoryName);
-            ensureRequiredNamesPresent(repositoryName, repositoryData);
-            loadSnapshotInfos(getAsyncSnapshotInfoIterator(repository, repositoryData), listener);
-        }
-
         /**
          * Check that the repository contains every <i>required</i> name according to {@link #snapshotNamePredicate}.
          *
@@ -459,54 +459,45 @@ public class TransportGetSnapshotsAction extends TransportMasterNodeAction<GetSn
             final List<SnapshotInfo> snapshots = new ArrayList<>();
             final List<SnapshotInfo> syncSnapshots = Collections.synchronizedList(snapshots);
 
-            SubscribableListener
-
-                .<Void>newForked(l -> {
-                    try (var listeners = new RefCountingListener(l)) {
-                        ThrottledIterator.run(
-                            Iterators.failFast(asyncSnapshotInfoIterator, () -> cancellableTask.isCancelled() || listeners.isFailing()),
-                            (ref, asyncSnapshotInfo) -> {
-                                final var refListener = ActionListener.runBefore(listeners.acquire(), ref::close);
-                                asyncSnapshotInfo.getSnapshotInfo(new ActionListener<>() {
-                                    @Override
-                                    public void onResponse(SnapshotInfo snapshotInfo) {
-                                        if (matchesPredicates(snapshotInfo)) {
-                                            repositoryTotalCount.incrementAndGet();
-                                            if (afterPredicate.test(snapshotInfo)) {
-                                                syncSnapshots.add(snapshotInfo.maybeWithoutIndices(indices));
-                                            }
-                                        }
-                                        refListener.onResponse(null);
-                                    }
-
-                                    @Override
-                                    public void onFailure(Exception e) {
-                                        if (ignoreUnavailable) {
-                                            logger.warn(Strings.format("failed to fetch snapshot info for [%s]", asyncSnapshotInfo), e);
-                                            refListener.onResponse(null);
-                                        } else {
-                                            refListener.onFailure(e);
-                                        }
+            try (var listeners = new RefCountingListener(listener)) {
+                final var iterationCompleteListener = listeners.acquire(ignored -> {
+                    totalCount.addAndGet(repositoryTotalCount.get());
+                    // no need to synchronize access to snapshots: all writes happen-before this read
+                    resultsCount.addAndGet(snapshots.size());
+                    allSnapshotInfos.add(snapshots);
+                });
+                ThrottledIterator.run(
+                    Iterators.failFast(asyncSnapshotInfoIterator, () -> cancellableTask.isCancelled() || listeners.isFailing()),
+                    (ref, asyncSnapshotInfo) -> {
+                        final var refListener = ActionListener.runBefore(listeners.acquire(), ref::close);
+                        asyncSnapshotInfo.getSnapshotInfo(new ActionListener<>() {
+                            @Override
+                            public void onResponse(SnapshotInfo snapshotInfo) {
+                                if (matchesPredicates(snapshotInfo)) {
+                                    repositoryTotalCount.incrementAndGet();
+                                    if (afterPredicate.test(snapshotInfo)) {
+                                        syncSnapshots.add(snapshotInfo.maybeWithoutIndices(indices));
                                     }
-                                });
-                            },
-                            getSnapshotInfoExecutor.getMaxRunningTasks(),
-                            () -> {},
-                            () -> {}
-                        );
-                    }
-                })
-
-                // no need to synchronize access to snapshots: all writes happen-before this read
-                .andThenAccept(ignored -> addResults(repositoryTotalCount.get(), snapshots))
-
-                .addListener(listener);
-        }
+                                }
+                                refListener.onResponse(null);
+                            }
 
-        private void addResults(int repositoryTotalCount, List<SnapshotInfo> snapshots) {
-            totalCount.addAndGet(repositoryTotalCount);
-            resultsCount.addAndGet(snapshots.size());
-            allSnapshotInfos.add(snapshots);
+                            @Override
+                            public void onFailure(Exception e) {
+                                if (ignoreUnavailable) {
+                                    logger.warn(Strings.format("failed to fetch snapshot info for [%s]", asyncSnapshotInfo), e);
+                                    refListener.onResponse(null);
+                                } else {
+                                    refListener.onFailure(e);
+                                }
+                            }
+                        });
+                    },
+                    getSnapshotInfoExecutor.getMaxRunningTasks(),
+                    () -> {},
+                    () -> iterationCompleteListener.onResponse(null)
+                );
+            }
         }
 
         private GetSnapshotsResponse buildResponse() {