Remove clusterAlias instance member from QueryShardContext (#37923)

The clusterAlias member is only used in the copy constructor, to be able
to reconstruct the fully qualified index. It is also possible to remove
the instance member and add a private constructor that accepts the already built Index object which contains the cluster alias.

Author: javanna

Diff for: server/src/main/java/org/elasticsearch/index/query/QueryShardContext.java

@@ -86,7 +86,6 @@ public class QueryShardContext extends QueryRewriteContext {
     private final BiFunction<MappedFieldType, String, IndexFieldData<?>> indexFieldDataService;
     private final int shardId;
     private final IndexReader reader;
-    private final String clusterAlias;
     private String[] types = Strings.EMPTY_ARRAY;
     private boolean cacheable = true;
     private final SetOnce<Boolean> frozen = new SetOnce<>();
@@ -110,6 +109,23 @@ public QueryShardContext(int shardId, IndexSettings indexSettings, BitsetFilterC
                              SimilarityService similarityService, ScriptService scriptService, NamedXContentRegistry xContentRegistry,
                              NamedWriteableRegistry namedWriteableRegistry, Client client, IndexReader reader, LongSupplier nowInMillis,
                              String clusterAlias) {
+        this(shardId, indexSettings, bitsetFilterCache, indexFieldDataLookup, mapperService, similarityService, scriptService,
+            xContentRegistry, namedWriteableRegistry, client, reader, nowInMillis, new Index(RemoteClusterAware.buildRemoteIndexName(
+                clusterAlias, indexSettings.getIndex().getName()), indexSettings.getIndex().getUUID()));
+    }
+
+    public QueryShardContext(QueryShardContext source) {
+        this(source.shardId, source.indexSettings, source.bitsetFilterCache, source.indexFieldDataService, source.mapperService,
+                source.similarityService, source.scriptService, source.getXContentRegistry(), source.getWriteableRegistry(),
+                source.client, source.reader, source.nowInMillis, source.fullyQualifiedIndex);
+        this.types = source.getTypes();
+    }
+
+    private QueryShardContext(int shardId, IndexSettings indexSettings, BitsetFilterCache bitsetFilterCache,
+                             BiFunction<MappedFieldType, String, IndexFieldData<?>> indexFieldDataLookup, MapperService mapperService,
+                             SimilarityService similarityService, ScriptService scriptService, NamedXContentRegistry xContentRegistry,
+                             NamedWriteableRegistry namedWriteableRegistry, Client client, IndexReader reader, LongSupplier nowInMillis,
+                             Index fullyQualifiedIndex) {
         super(xContentRegistry, namedWriteableRegistry,client, nowInMillis);
         this.shardId = shardId;
         this.similarityService = similarityService;
@@ -121,16 +137,7 @@ public QueryShardContext(int shardId, IndexSettings indexSettings, BitsetFilterC
         this.scriptService = scriptService;
         this.indexSettings = indexSettings;
         this.reader = reader;
-        this.clusterAlias = clusterAlias;
-        this.fullyQualifiedIndex = new Index(RemoteClusterAware.buildRemoteIndexName(clusterAlias, indexSettings.getIndex().getName()),
-            indexSettings.getIndex().getUUID());
-    }
-
-    public QueryShardContext(QueryShardContext source) {
-        this(source.shardId, source.indexSettings, source.bitsetFilterCache, source.indexFieldDataService, source.mapperService,
-                source.similarityService, source.scriptService, source.getXContentRegistry(), source.getWriteableRegistry(),
-                source.client, source.reader, source.nowInMillis, source.clusterAlias);
-        this.types = source.getTypes();
+        this.fullyQualifiedIndex = fullyQualifiedIndex;
     }
 
     private void reset() {