In #16624, I introduced a new mechanism to record imports to other
modules, instead of having specialized datetime/typing/pydantic objects
to manage imports for these modules.
This change reuses the mechanism from #16624 and replace the specialized
import managers by the generic one. Unused imports from various
.mustache templates are also cleaned up.
* updating test to use the Java RESTEasy echo api client (#17367)
* regenerated samples
* set source and target to 1.8 to fix workflow failure, adapted parser
