code: public static <TExpression> Bson bucketAuto(final TExpression groupBy, final int buckets, final BucketAutoOptions options) {
          return new BucketAutoStage<TExpression>(groupBy, buckets, options);
      }
docs: Creates a $bucketAuto pipeline stage
  
  @param <TExpression> the groupBy expression type
  @param groupBy       the criteria to group By
  @param buckets       the number of the buckets
  @param options       the optional values for the $bucketAuto stage
  @return the $bucketAuto pipeline stage
  @mongodb.driver.manual reference/operator/aggregation/bucketAuto/ $bucketAuto
  @mongodb.server.release 3.4
  @since 3.4