How to add a default codec for internal objects of an entity

[victorGS18]

I'm having problems reading an object that has another object defined inside. It tells me that it doesn't find a codec and therefore I would like to add a default pojoCodec as is possible in the driver.

The codecRegistry would be this:
MongoClientSettings.getDefaultCodecRegistry(), CodecRegistries.fromProviders(PojoCodecProvider.builder().automatic(true).build())

The problem is that if I add this to MapperOptions then it adds them before the Morphia Codecs and then the aggregations don't work, for example, the $match expression decodes it with the default codec.

Is there a way to do this?
Or what is the solution for internal objects of an entity?

Thanks!

** Please complete the following information: **
Morphia Version: 2.4.14

[victorGS18]

What I want is to avoid having to annotate 300 internal classes with @Entity