code: public PushOptions sort(@Nullable final Integer sort) {
          if (sortDocument != null) {
              throw new IllegalStateException("sort can not be set if sortDocument already is");
          }
          this.sort = sort;
          return this;
      }
docs: Sets the sort direction for sorting array elements that are not documents.
  
  @param sort the sort direction
  @return this
  @throws IllegalStateException if sortDocument property is already set
  @mongodb.driver.manual reference/operator/update/sort/ $sort
  @mongodb.driver.manual reference/operator/update/sort/#sort-array-elements-that-are-not-documents