Dry up Common Fields

[original-brownbear]

There is a lot of code duplication across all schemata coming from the common fields. Since we don't have inheritance in AVRO their code is currently duplicated across all other schemata.

• Question 1: Do we want to fix this?
• Question 2: If yes, what kind of fix do we want?
  • I see two possible approaches here:
    • If we want to keep the 1:1 correspondence between JSON and AVRO field hierarchy, then we could try to generate the AVRO sources before actually compiling them with the AVRO compiler. Concretely, we could have a placeholder {{common_fields}} or so that we can put in an avsc file and have Maven replace it with the common field code before compilation.
    • Better option: If we can live with having the AVRO and JSON hierarchy no correspond 1:1 then we could simply create a record schema CommonFields that has all the common fields in it and put it at the top level of all the other schemata under a key common_fields or so.

[acmeguy]

I suggest a third option and would like to know what you think about it.

Let's consolidate the sub-type classes like you suggest for Video events and leave the redundancy as it is. (That way there are a lot fever files/sub-classes involved)

[original-brownbear]

@acmeguy

If that's an appropriate level of validation for you still, I like that approach. As far as I can see we have no type collisions between properties of various kind of mobile events and such so that should work out fine.

[acmeguy]

great. I think that this is also more flexible and re-usable for anyone wanting to use this lib.

[original-brownbear]

Closing here, will handle the remaining bits in #5