code: public Transactions getTransactions(final TransactionState state, final TransactionType type, final QueryParams params) {
          if (state != null) params.put("state", state.getType());
          if (type != null) params.put("type", type.getType());
  
          return doGET(Transactions.TRANSACTIONS_RESOURCE, Transactions.class, params);
      }
docs: Get site's transaction history
  <p>
  All transactions on the site
  
  @param state {@link TransactionState}
  @param type {@link TransactionType}
  @param params {@link QueryParams}
  @return the transaction history of the site on success, null otherwise