Revert exposed `readText` method.

Change-Id: I8076fabed4b4f2f460c74b43ad1c3e38a5268005

core/network/src/main/kotlin/JvmUnitTestDemoAssetManager.kt

@@ -17,7 +17,6 @@
 import com.google.samples.apps.nowinandroid.core.network.demo.DemoAssetManager
 import java.io.File
 import java.io.InputStream
-import java.nio.charset.StandardCharsets
 import java.util.Properties
 
 /**
@@ -39,5 +38,4 @@ internal object JvmUnitTestDemoAssetManager : DemoAssetManager {
     private val assets = File(properties["android_merged_assets"].toString())
 
     override fun open(fileName: String): InputStream = File(assets, fileName).inputStream()
-    override fun readText(fileName: String): String = File(assets, fileName).readText(StandardCharsets.UTF_8)
 }

core/network/src/main/kotlin/com/google/samples/apps/nowinandroid/core/network/demo/DemoAssetManager.kt

@@ -18,7 +18,6 @@ package com.google.samples.apps.nowinandroid.core.network.demo
 
 import java.io.InputStream
 
-interface DemoAssetManager {
+fun interface DemoAssetManager {
     fun open(fileName: String): InputStream
-    fun readText(fileName: String): String
 }

core/network/src/main/kotlin/com/google/samples/apps/nowinandroid/core/network/di/NetworkModule.kt

@@ -32,7 +32,6 @@ import kotlinx.serialization.json.Json
 import okhttp3.Call
 import okhttp3.OkHttpClient
 import okhttp3.logging.HttpLoggingInterceptor
-import java.io.InputStream
 import javax.inject.Singleton
 
 @Module
@@ -49,10 +48,7 @@ internal object NetworkModule {
     @Singleton
     fun providesDemoAssetManager(
         @ApplicationContext context: Context,
-    ): DemoAssetManager = object : DemoAssetManager {
-        override fun open(fileName: String): InputStream = context.assets.open(fileName)
-        override fun readText(fileName: String): String = context.assets.open(fileName).bufferedReader().use { it.readText() }
-    }
+    ): DemoAssetManager = DemoAssetManager(context.assets::open)
 
     @Provides
     @Singleton