Adding two HH:mm time values in Talend Data Integration

Question

I have got a requirement to push the data from excel to database. Excel has few columns that are automated with formulas:

In the job, I am using tFileInputExcel >> tMap >> database. In the tMap:

To create a variable for B2-A2 (Break Time - Start Time):

1. ms -- TalendDate.diffDate(row1.Time_Isolated,row1.Error_Time,"SSS")
2. total_time -- String.format("%02d:%02d", (Var.ms / (1000 * 60 * 60)) % 24, (Var.ms / (1000 * 60)) % 60)
3. var1 -- TalendDate.parseDate("HH:mm",Var.total_time)

Var.var1 shows the difference in HH:mm. Likewise, I did for D2-C2 (End Time - Restart Time) and got the difference in HH:mm.

Now, need a bit of help to add these two variables to sum up the two values in HH:mm

Appreciate any help here. Thanks...