make copy

Author: smalyshev

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/EsqlSession.java

@@ -83,6 +83,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -344,7 +345,7 @@ public void analyzedPlan(
             return plan;
         };
         // Capture configured remotes list to ensure consistency throughout the session
-        executionInfo.setConfiguredClusters(indicesExpressionGrouper.getConfiguredClusters());
+        executionInfo.setConfiguredClusters(Set.copyOf(indicesExpressionGrouper.getConfiguredClusters()));
 
         PreAnalyzer.PreAnalysis preAnalysis = preAnalyzer.preAnalyze(parsed);
         var unresolvedPolicies = preAnalysis.enriches.stream()