that is defined here :

@Module
@InstallIn(ApplicationComponent::class)
class NetworkModule {

    @Provides
    fun provideCache(@ApplicationContext context: Context): Cache? {
        val cacheSize = 10 * 1024 * 1024L // 10MB
        var cache: Cache? = null
        // Install an HTTP cache in the application cache directory.
        try {
            val cacheDir = File(context.cacheDir, "http")
            cache = Cache(cacheDir, cacheSize)
        } catch (e: Exception) {
            Timber.e(e, "Unable to install disk cache.")
        }

        return cache
    }

   // Other dependencies ...

}