Ref #18 - Add incremental annotation processing

[mtraynham]

Related to #18

This adds incremental annotation processing for faster gradle builds.

By adding src/main/resources/META-INF/gradle/incremental.annotation.processors, it tells Gradle that the com.github.pozo.BuilderProcessor is an incremental processor.

A bump to MapStruct 1.4.0.Beta1 (mapstruct/mapstruct#1971) and AutoService 1.0-rc.7 (google/auto#615) is required.

[mtraynham]

@Pozo any chance you could take a look at this? I know it might be better if the mapstruct version was final and not a Beta version.

[Pozo]

@mtraynham Sure, so sorry for the late answer. I have a lot of thing going on, that's why I couldn't look over this repo changes nowadays. I'll manage everything soon, thank you very much for your time and your contribution. 🙇

[Pozo]

I've tested it locally with the following environment

------------------------------------------------------------
Gradle 4.10
------------------------------------------------------------

Build time:   2018-08-27 18:35:06 UTC
Revision:     ee3751ed9f2034effc1f0072c2b2ee74b5dce67d

Kotlin DSL:   1.0-rc-3
Kotlin:       1.2.60
Groovy:       2.4.15
Ant:          Apache Ant(TM) version 1.9.11 compiled on March 23 2018
JVM:          1.8.0_252 (AdoptOpenJDK 25.252-b09)
OS:           Mac OS X 10.13.6 x86_64

With the command

./gradlew clean build --info

With the version 1.3.1.2 I'm getting the following output

[kapt] Incremental annotation processing requested, but support is disabled because the following processors are not incremental: com.github.pozo.BuilderProcessor (NON_INCREMENTAL), org.mapstruct.ap.MappingProcessor (NON_INCREMENTAL), com.google.auto.service.processor.AutoServiceProcessor (NON_INCREMENTAL).

With your change this message disappears. Thank you for your contribution @mtraynham

I'll prepare a release the version number will be 1.4.0.0

[mtraynham]

@Pozo awesome! One thing I wanted to point out, the Mapstruct version I bumped is the beta release 1.4.0.Beta1, https://github.com/mapstruct/mapstruct/releases/tag/1.4.0.Beta1. 1.4.0.Beta3 is also out now and I've verified it also works locally, https://github.com/mapstruct/mapstruct/releases/tag/1.4.0.Beta3. You can circumvent this in downstream projects by forcing the mapstruct version to a later or earlier one.

Not sure if you want to do a full release with a beta dependency, or just have your own beta release. Either way, I can finally start using incremental processing 😄, so thank you!