Retrofit 2 example tutorial but GsonConverterFactory display error “Cannot resolve symbol”

EDIT

retrofit 2 is now stable. Use

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'

in your build.gradle dependency section

old answer

with Retrofit 2.0 you have to declare in your build.gradle the convert factory you want to use. Add

compile 'com.squareup.retrofit:converter-gson:2.0.0-beta2'

to your gradle and sync it again