Fix: Explicitly reconstruct map for FunctionCallPartDto mapping

Addresses a persistent compilation type mismatch error in PhotoReasoningMappers.kt when mapping FunctionCallPartDto to the SDK's FunctionCallPart, specifically for the 'args' field. Previous attempts using direct assignment and explicit casting did not resolve the issue where the compiler reported a mismatch despite seemingly identical types (Map<String, String?>?).

This commit modifies the `PartDto.toSdk()` function for the `FunctionCallPartDto` case. Instead of directly passing or casting `this.args`, a new `Map<String, String?>` is explicitly constructed by iterating over the entries of `this.args` (if not null) and populating the new map.

This explicit reconstruction provides a 'fresh' map instance with a clearly defined type to the SDK's `FunctionCallPart` constructor, aiming to resolve any subtle type system incompatibilities that the compiler might have been struggling with.

Author: google-labs-jules[bot]

app/src/main/kotlin/com/google/ai/sample/feature/multimodal/dtos/PhotoReasoningMappers.kt

@@ -55,7 +55,18 @@ fun PartDto.toSdk(): Part { // No context needed here as path is absolute
                 ?: throw IllegalArgumentException("Failed to load Bitmap from file path: ${this.imageFilePath}, or file was invalid.")
         }
         is BlobPartDto -> BlobPart(mimeType = this.mimeType, blob = this.data)
-        is FunctionCallPartDto -> FunctionCallPart(name = this.name, args = this.args as Map<String, String?>?)
+        is FunctionCallPartDto -> {
+            val sdkArgs: Map<String, String?>? = this.args?.let { dtoArgs ->
+                // Explicitly create a new map to ensure the compiler understands the type correctly.
+                val newMap = mutableMapOf<String, String?>()
+                dtoArgs.entries.forEach { entry -> // Iterate through entries
+                    newMap[entry.key] = entry.value
+                }
+                newMap.toMap() // Convert to immutable Map if constructor expects Map, or just newMap if MutableMap is fine.
+                               // Assuming FunctionCallPart constructor takes Map<String, String?>?
+            }
+            FunctionCallPart(name = this.name, args = sdkArgs)
+        }
         is FunctionResponsePartDto -> {
             // Convert responseJson String back to org.json.JSONObject
             val jsonObject = try {