ngInjectorDef.imports is generated from @NgModule.imports plus
@NgModule.exports. A problem arises as a result, because @NgModule
exports contain not only other modules (which will have ngInjectorDef
fields), but components, directives, and pipes as well. Because of
locality, it's difficult for the compiler to filter these out at
build time.
It's not impossible, but for now filtering them out at runtime will
allow testing of the compiler against complex applications.
PR Close#24862