I always recommend pulling out those versions into...

# rx

[kevinmost]

I always recommend pulling out those versions into a variable, so that you don't ever let them get out of sync.

ext.versions = [
    retrofit: "2.1.0",
]

compile "com.squareup.retrofit2:retrofit:$versions.retrofit"
compile "com.squareup.retrofit2:adapter-rxjava:$versions.retrofit"