CloudEventUtils.mapData(event, mapper)

[slinkydeveloper]

This PR adds a new method to CloudEventUtils, called mapData(event, mapper) (implemented by default), to improve the user experience with mappers. Now we finally have a good user experience for data: users can now safely map event payloads to business objects without casting and without any knowledge of the sdk itself:

MyPojo myPojo = mapData(event, PojoCloudEventDataMapper.from(objectMapper, new TypeReference<MyPojo>() {})) // PojoCloudEventDataMapper<MyPojo>
  .getValue();

(note: this example is using json mapper which is proposed in another pr independent from this one)

To make this possible, I also generified the return value of CloudEventDataMapper

Signed-off-by: Francesco Guardiani francescoguard@gmail.com

[olegz]

As it was debated many times before this change violates the consistency and simplicity of the core interface.
So -1

Tagging @n3wscott @duglin as I already have an open complaint about a PR being merged with no consensus reached - #250 (comment)

[slinkydeveloper]

Related to #258

[johanhaleby]

My feeling is that serialization/conversion should not be a part of the interface, it's a separate concern.

It would be OK if it was an extension function provided by the serialization library/module.

[slinkydeveloper]

@johanhaleby Except we don't have extensions in java 😄 How about moving to some utils class, like CloudEventUtils in core?

[slinkydeveloper]

Moved, now it should be better

[aliok]

This seems like the next natural step after the previous improvements.
Makes more sense with #258.

/lgtm

[pierDipi]

LGTM