code: private DescribeRouteTablesResponseType describeRouteTables() {
          DescribeRouteTablesResponseType ret = new DescribeRouteTablesResponseType();
          ret.setRequestId(UUID.randomUUID().toString());
  
          RouteTableSetType routeTableSet = new RouteTableSetType();
          for (Iterator<MockRouteTable> mockRouteTable = mockRouteTableController
                  .describeRouteTables().iterator(); mockRouteTable.hasNext();) {
              MockRouteTable item = mockRouteTable.next();
  
              RouteTableType routeTable = new RouteTableType();
              if (!DEFAULT_MOCK_PLACEMENT.getAvailabilityZone().equals(currentRegion)) {
                  routeTable.setVpcId(currentRegion + "_" + item.getVpcId());
                  routeTable.setRouteTableId(currentRegion + "_" + item.getRouteTableId());
              } else {
                  routeTable.setVpcId(item.getVpcId());
                  routeTable.setRouteTableId(item.getRouteTableId());
              }
  
              RouteTableAssociationSetType associationSet = new RouteTableAssociationSetType();
              routeTable.setAssociationSet(associationSet);
  
              RouteSetType routeSet = new RouteSetType();
              routeTable.setRouteSet(routeSet);
  
              routeTableSet.getItem().add(routeTable);
          }
  
          ret.setRouteTableSet(routeTableSet);
  
          return ret;
      }
docs: Handles "describeRouteTables" request and returns response with a route table.
  
  @return a DescribeRouteTablesResponseType with our predefined route table in aws-mock.properties (or if not
  overridden, as defined in aws-mock-default.properties)