signature(rootProject.libs.signature.android.apilevel24) { artifact { type = "signature" } }
    } else {
      // Everything else requires Android API 21+.
      signature(rootProject.libs.signature.android.apilevel21) { artifact { type = "signature" } }
    }

    // OkHttp requires Java 8+.
    signature(rootProject.libs.codehaus.signature.java18) { artifact { type = "signature" } }
  }

  tasks.withType<KotlinCompile> {