Why do I have to specify both 'runtime' and 'compile' for the same dependency?

Question

I am depending on a few artifacts that I need to both compile and run my application.

According to the Gradle docs, the runtime configuration extends the compil

Answer 1

Almost right. Runtime configuration, indeed, extends compile configuration (docs). It means, that any dependency added to compile configuration is available in runtime configuration (docs).

compile 'oauth.signpost:signpost-core:1.2.1.2' will be enough to get this artifact in both, runtime and compile.