Upgrade Fortify from 17.20 to 19.20

Dear All,

We are currently using Fortify 17.20 in our current pipeline and we want to upgrade it to 19.20.

However Microfocus told us that, we cant have a direct upgrade to 19.20, we must need to upgrade to either 18.20 or 19.10 before we actually migrate to 19.20.

We can install 18.20 or 19.10 on our machines, but  i am concerned about existing project migrations from 17.20. 

Do we need to migrate all project to 18.20 or19.10 and then migrate to 19.20 along with the application server upgrade, or we need to do only application server upgrade from 17.20 to 18.20 or 19.10 and then upgrade all projects to 19.20. Could you please help me regarding this?