Task for PMD, Checkstyle, Findbugs

Hi Stephane,

Really thank you for this awesome work !

I was playing with it, and I did not really understood why we need to use task for launching PMD, Checkstyle, or Findbugs. Is this a limitation of the current android plugin for Gradle ? Obviously there is something wrong since if I want to configure for example the checkstyle source without using a task with something like that :

checkstyle {
configFile file("${project.rootDir}/config/quality/checkstyle/checkstyle.xml")
source 'src'
include 'some java files'
exclude 'the gen folder'
classpath = files()
}

Gradle will give me this result :
unsupported Gradle DSL method found :'source()'

Of course the solution of using a task works perfectly but I really would like to understand why we have to do this way :)

And again, thank for sharing this awesome work !