Consider merging duplicate key criteria with $and instead of throwing an exception in Query#addCriteria

When building queries dynamically, it's fairly common to end up calling addCriteria() multiple times with criteria that share the same key — for example, applying both a lower and upper bound on the same field via separate code paths.

Currently, addCriteria() throws an InvalidMongoDbApiUsageException in this case:

query.addCriteria(where("amount").gte(100));
query.addCriteria(where("amount").lte(500)); // throws

The workaround is to collect all criteria into a list and wrap them with andOperator(), which works fine but isn't obvious and forces callers to restructure their query-building logic just to avoid the exception.

It would be nice if addCriteria() (or a new variant) could automatically merge conflicting criteria under a $and instead of throwing. MongoDB handles this just fine:

{ "$and": [ { "amount": { "$gte": 100 } }, { "amount": { "$lte": 500 } } ] }

I understand there might be concerns around changing existing behavior, so a separate method like addCriteriaOrAnd() or a flag on Query could be an option.

Start at Query#addCriteria and trace the InvalidMongoDbApiUsageException path for duplicate keys. Compare it with the existing andOperator() behavior, then define and test whether duplicate criteria should merge under $and while preserving existing behavior for non-conflicting criteria.