fix integration test

Author: valeriy42

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/retention/ExpiredModelSnapshotsRemover.java

@@ -271,7 +271,14 @@ private void deleteModelSnapshots(List<ModelSnapshot> modelSnapshots, String job
         }
 
         // Remove read-only indices
-        var indicesToQuery = writableIndexExpander.getWritableIndices(indices);
+        List<String> indicesToQuery = new ArrayList<>();
+        try {
+            indicesToQuery = writableIndexExpander.getWritableIndices(indices);
+        } catch (Exception e) {
+            LOGGER.error("Failed to get writable indices for [{}] job: {}", jobId, e.getMessage(), e);
+            listener.onFailure(e);
+            return;
+        }
         if (indicesToQuery.isEmpty()) {
             LOGGER.info("No writable model snapshot indices found for [{}] job. No expired model snapshots to remove.", jobId);
             listener.onResponse(true);

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/retention/WritableIndexExpander.java

@@ -15,6 +15,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.List;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -33,22 +34,29 @@ public WritableIndexExpander(ClusterService clusterService, IndexNameExpressionR
     }
 
     protected ArrayList<String> getWritableIndices(String indexPattern) {
-        var clusterState = clusterService.state();
-        var concreteIndices = indexNameExpressionResolver.concreteIndexNames(
-            clusterState,
-            IndicesOptions.LENIENT_EXPAND_OPEN_HIDDEN,
-            indexPattern
-        );
-        return Arrays.stream(concreteIndices)
-            .filter(index -> isIndexReadOnly(index) == false)
-            .collect(Collectors.toCollection(ArrayList::new));
+        return getWritableIndices(List.of(indexPattern));
     }
 
     protected ArrayList<String> getWritableIndices(Collection<String> indices) {
-        return indices.stream().filter(index -> isIndexReadOnly(index) == false).collect(Collectors.toCollection(ArrayList::new));
+        if (indices == null || indices.isEmpty()) {
+            return new ArrayList<>();
+        }
+        var clusterState = clusterService.state();
+        return indices.stream()
+            .map(index -> indexNameExpressionResolver.concreteIndexNames(clusterState, IndicesOptions.LENIENT_EXPAND_OPEN_HIDDEN, index))
+            .flatMap(Arrays::stream)
+            .filter(index -> (isIndexReadOnly(index) == false))
+            .collect(Collectors.toCollection(ArrayList::new));
     }
 
     private Boolean isIndexReadOnly(String indexName) {
-        return IndexMetadata.INDEX_BLOCKS_WRITE_SETTING.get(clusterService.state().metadata().getProject().index(indexName).getSettings());
+        IndexMetadata indexMetadata = clusterService.state().metadata().getProject().index(indexName);
+        if (indexMetadata == null) {
+            throw new IllegalArgumentException("Failed to identify if index is read-only: index [" + indexName + "] not found");
+        }
+        if (indexMetadata.getSettings() == null) {
+            throw new IllegalStateException("Settings for index [" + indexName + "] are unavailable");
+        }
+        return IndexMetadata.INDEX_BLOCKS_WRITE_SETTING.get(indexMetadata.getSettings());
     }
 }

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/job/retention/ExpiredResultsRemoverTests.java

@@ -201,8 +201,6 @@ private void givenBucket(Bucket bucket) {
         }).when(client).execute(eq(TransportSearchAction.TYPE), any(), any());
     }
 
-
-
     private ExpiredResultsRemover createExpiredResultsRemover(Iterator<Job> jobIterator) {
         return createExpiredResultsRemover(jobIterator, true);
     }