I have a 1.x management pack with some alert definitions defined in descirbe.xml.
In 2.x we have removed some alert definitions from describe.xml and increased descibe.xml version.
Now when I upgraded management pack from 1.x to 2.x (i dint selected - Reset to default option while upgrading)
once the installation is completed. I'm still seeing old Alert Definitions in the Alert Settings.
I haven't changed any code in the adapter. my expectation is while upgrading the management pack it will call onDescribe() method, redescribe should happen and older Alert Definitions should go away.
Note: when I selected the checkbox - Reset to default option, older Alert definitions are removed.
is it necessary to check - Reset to default, while upgrading the management pack if something is removed from older version to newer version?
Yes, it's necessary to check that box for the reasons you described. Any existing artifacts employed by the previous version of the management pack such as views and reports will not get overwritten unless you do so.