How to download javadocs and sources for jar using Gradle 2.0?

You can write an ArtifactResolutionQuery that copies all SourcesArtifact and JavadocArtifact for each of your dependencies

See here for an example and here for the gradle source code which does it for the Eclipse/Intellij plugins

In addition to previous question, here is Gradle Kotlin DSL version:

plugins {
    id("idea")
}

idea {
    module {
        isDownloadJavadoc = true
        isDownloadSources = true
    }
}

I guess your question is related to a dev workspace, here are links explaining how to add the required configuration in Gradle using the IDEs' plugins:

For Eclipse:

apply plugin: 'java'
apply plugin: 'eclipse'

eclipse {
    classpath {
        downloadJavadoc = true
        downloadSources = true
    }
}

For IntelliJ & Android Studio

apply plugin: 'java'
apply plugin: 'idea'

idea {
    module {
        downloadJavadoc = true
        downloadSources = true
    }
}

To run these plugins:

gradle cleanEclipse eclipse
gradle cleanIdea idea