Inject Base<Type> before preparing phase, inject <Type> at preparing and later

[Tcharl]

Overview of the feature request

'preparing' phase is done to hydrate objects. Ideally the generator should follow that principle and inject the right kind of type whenever it is possible.

Motivation for or Use Case

Narrow the applicable fields at each generation step to enforce best convetions.

Related issues or PR

#30120

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