code: @Nonnull
    public Query endBefore(Object... fieldValues) {
      QueryOptions newOptions = new QueryOptions(options);
      newOptions.endCursor = createCursor(newOptions.fieldOrders, fieldValues, true);
      return new Query(firestore, path, newOptions);
    }
docs: Creates and returns a new Query that ends before the provided fields relative to the order of
  the query. The order of the field values must match the order of the order by clauses of the
  query.
  
  @param fieldValues The field values to end this query before, in order of the query's order by.
  @return The created Query.