chore: share openiap main sourceset

Author: hyochan

packages/google/openiap/build.gradle.kts

@@ -63,8 +63,20 @@ android {
         buildConfig = true
     }
 
-    // Source sets are automatically configured per flavor
+    // Source sets configuration
+    // main/ is shared across all flavors
     // play/ and horizon/ directories are used by their respective flavors
+    sourceSets {
+        getByName("main") {
+            java.srcDirs("src/main/java")
+        }
+        getByName("play") {
+            java.srcDirs("src/play/java", "src/main/java")
+        }
+        getByName("horizon") {
+            java.srcDirs("src/horizon/java", "src/main/java")
+        }
+    }
 }
 
 dependencies {