Bundle proguard rules for Android (#834)

Refs https://square.github.io/okhttp/features/r8_proguard/.

Author: Goooler

docs/CHANGELOG.md

@@ -7,6 +7,16 @@ and this project orients towards [Semantic Versioning](http://semver.org/spec/v2
 Note: This project needs KSP to work and every new Ktorfit with an update of the KSP version is technically a breaking change.
 But there is no intent to bump the Ktorfit major version for every KSP update. 
 
+
+# [Unreleased]()
+
+Unreleased - 2025-xx-xx
+========================================
+
+## Added
+- Bundle proguard rules for Android
+
+
 # [2.4.1]()
 
 2.4.1 - 2025-03-14

docs/android/proguard.md

@@ -1,5 +1,4 @@
-proguard-rules.pro
-```
--keep class de.jensklingenberg.ktorfit.** { *; }
--keepclassmembers class de.jensklingenberg.ktorfit.** { *; }
-```
+If you use Ktorfit as a dependency in an Android project which uses R8 as a default compiler you don’t have to 
+do anything. The specific rules are 
+[already bundled](../../ktorfit-lib-core/src/jvmMain/resources/META-INF/proguard/ktorfit.pro) into the JAR 
+which can be interpreted by R8 automatically.

ktorfit-lib-core/build.gradle.kts

@@ -173,6 +173,17 @@ android {
     defaultConfig {
         minSdk = 21
         targetSdk = 34
+
+        val proguardFile =
+            file("src/jvmMain/resources/META-INF/proguard/ktorfit.pro").also {
+                if (!it.exists()) {
+                    throw NoSuchFileException(
+                        file = it,
+                        reason = "We have to provide a proguard rules file for the library.",
+                    )
+                }
+            }
+        consumerProguardFiles(proguardFile)
     }
     namespace = "de.jensklingenberg.ktorfit.common"
 }

ktorfit-lib-core/src/jvmMain/resources/META-INF/proguard/ktorfit.pro

@@ -0,0 +1,2 @@
+-keep class de.jensklingenberg.ktorfit.** { *; }
+-keepclassmembers class de.jensklingenberg.ktorfit.** { *; }