driver-core/src/main/com/mongodb/operation/AggregateExplainOperation.java
public AggregateExplainOperation hint(final BsonValue hint) {
        isTrueArgument("BsonString or BsonDocument", hint == null || hint.isDocument() || hint.isString());
        this.hint = hint;
        return this;
    }
public AggregateExplainOperation hint(final BsonValue hint) {
        isTrueArgument("BsonString or BsonDocument", hint == null || hint.isDocument() || hint.isString());
        this.hint = hint;
        return this;
    }
Sets the hint for which index to use. A null value means no hint is set.

@param hint the hint
@return this
@since 3.6
@mongodb.server.release 3.6