Reduce dependency list

[emilianbold]

It would be nice to restrict the dependency list to a minimum:

• I see 4 logging dependencies while none is required (except as a transitive dependency from HttpClient5)
• the javax.validation dependency is not really required as those annotations, while useful, are used in a single class. (And, I would say, there are better libraries that provide such annotations).

[HanSolo]

I agree, I also saw the useless logging dependencies...

[aalmiray]

The minimum set of dependencies may be

    implementation("com.google.code.gson:gson:2.8.8")
    implementation("org.slf4j:slf4j-api:1.7.25")

Also, set them in the api scope.

The log4j dependencies might be needed for testing, if so move them to testImplementation scope.

[aalmiray]

And don't forget to bump the slf4j-api version to the latest release 😉