NCML Time axis aggregation with missing / time gaps about thredds HOT 6 CLOSED

datetime-start, datetime-end, file
2012-10-13 10:00:00, 2013-11-24 08:00:00, f1.nc  
            --- here data missing -- between 2013-11-24 08:01:00 to 2013-11-24 00:59:00
2013-11-24 13:00:00, 2014-11-15 15:00:00, f2.nc  
            --- here data missing -- between 2014-11-15 15:01:00 to 2016-11-16 00:59:00
2016-11-16 13:00:00, 2017-10-08 08:00:00, f3.nc  
            --- again here
2017-10-08 12:20:00, 2018-10-10 08:20:00, f4.nc  
            --- again here
2018-10-10 14:40:00, 2019-10-22 08:40:00, f5.nc  

# for f1.nc  
float Time(Time) ;
		Time:long_name = "Time" ;
		Time:units = "hours" ;
		Time:time_origin = "13-OCT-2012 10:00:00" ;

# for f2.nc  
float Time(Time) ;
		Time:long_name = "Time" ;
		Time:units = "hours" ;
		Time:time_origin = "24-NOV-2013 13:00:00" ;

$ ncdump -h f1.nc | grep 'Time = '
	Time = 9767 ;
$ ncdump -h f2.nc | grep 'Time = '
	Time = 8547 ;
$ ncdump -h f3.nc | grep 'Time = '
	Time = 7820 ;


netcdf file:test.ncml {
  dimensions:
    Lon = 1;
    Lat = 1;
    Depth = 63;
    Time = 26134;           /*  Here I need available plus missing hours */


 float Time(Time=26134);
      :long_name = "Time";
      :units = "hours";
      :time_origin = "13-OCT-2012 10:00:00"; /* Here I need  hours since 01-JAN-1970 00:00:00 */

<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2">
   <aggregation dimName="Time" type="joinExisting">
              
            <netcdf location="f1.nc" />
            <!-- Missing Here
                 How to define virtual dataset and fill with missing values 
                 between 2013-11-24 09:00:00 to 2013-11-24 00:00:00
            -->
            <netcdf location="f2.nc" />

            <!--- missing Here
                between 2014-11-15 16:00:00 to 2016-11-16 00:00:00
            -->

      
            <!-- can we convert these files time axis values relative to hours since 1970-JAN-01 00:00:00 -->
            <netcdf location="f3.nc" />

   </aggregation>
</netcdf>