code: public List<GenericTransaction> getDetails(final int year, final int month, final FeeDetailsType feeType,
              final PaginationParams pagination) throws OpenpayServiceException, ServiceUnavailableException {
          String path = String.format(FEES_DETAILS_PATH, this.getMerchantId());
          Map<String, String> params = new HashMap<String, String>();
          if (pagination != null) {
              params.putAll(pagination.asMap());
          }
          params.put("year", String.valueOf(year));
          params.put("month", String.valueOf(month));
          params.put("fee_type", feeType.name().toLowerCase());
          return this.getJsonClient().list(path, params, GenericTransaction.class);
      }
docs: Retrieves the list of transactions that affected the charged or refunded fees on a given month. Transactions in
  the CHARGED or REFUNDED type of detail add their fee to the total, while the ones in CHARGED_ADJUSTMENTS and
  REFUNDED_ADJUSTMENTS add their amount.
  @param year Year to report
  @param month Month to report
  @param feeType Type of the details to get.
  @param pagination Pagination. Optional, retrieves the latest 10 transactions if ommited.
  @return List of transactions that affect the fees in the given month.
  @throws ServiceUnavailableException
  @throws OpenpayServiceException