fix: Add path prefix presence flag and tests for AppFileInfo

src/main/java/in/dragonbra/javasteam/steam/handlers/steamcloud/AppFileInfo.kt

@@ -11,6 +11,7 @@ class AppFileInfo(response: CCloud_AppFileInfo) {
     val rawFileSize: Int = response.rawFileSize
     val persistState: ECloudStoragePersistState = response.persistState
     val platformsToSync: Int = response.platformsToSync
+    val hasPathPrefixIndex: Boolean = response.hasPathPrefixIndex()
     val pathPrefixIndex: Int = response.pathPrefixIndex
     val machineNameIndex: Int = response.machineNameIndex
 }

src/test/java/in/dragonbra/javasteam/steam/handlers/steamcloud/AppFileInfoTest.kt

@@ -0,0 +1,34 @@
+package `in`.dragonbra.javasteam.steam.handlers.steamcloud
+
+import `in`.dragonbra.javasteam.protobufs.steamclient.SteammessagesCloudSteamclient.CCloud_AppFileInfo
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+
+class AppFileInfoTest {
+
+    @Test
+    fun hasPathPrefixIndexIsFalseWhenFieldIsMissing() {
+        val response = CCloud_AppFileInfo.newBuilder()
+            .setFileName("save.dat")
+            .build()
+
+        val info = AppFileInfo(response)
+
+        assertFalse(info.hasPathPrefixIndex)
+    }
+
+    @Test
+    fun hasPathPrefixIndexIsTrueWhenIndexIsZero() {
+        val response = CCloud_AppFileInfo.newBuilder()
+            .setFileName("save.dat")
+            .setPathPrefixIndex(0)
+            .build()
+
+        val info = AppFileInfo(response)
+
+        assertTrue(info.hasPathPrefixIndex)
+        assertEquals(0, info.pathPrefixIndex)
+    }
+}