db.c.drop();

assert.commandWorked(db.adminCommand({setParameter: 1, internalQueryAllowAllPathsIndexes: true}));

db.c.insert({a: 1});
db.c.insert({a: {b: 1}});

assert.commandWorked(db.c.createIndex({"$**":1}));

const query = {a: {$in: [1, {b: 1}]}};
printjson(db.c.find(query).toArray());
printjson(db.c.explain("allPlansExecution").find(query).finish());