fix for issue with thought in parts sent as history for template chat

Author: David Motsonashvili

firebase-ai/src/main/kotlin/com/google/firebase/ai/TemplateGenerativeModel.kt

@@ -128,7 +128,7 @@ internal constructor(
   ): TemplateGenerateContentRequest {
     return TemplateGenerateContentRequest(
       Json.parseToJsonElement(JSONObject(inputs).toString()).jsonObject,
-      history?.let { it.map { it.toInternal() } }
+      history?.let { it.map { it.toInternal(nullPartThought = true) } }
     )
   }
 

firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Content.kt

@@ -85,7 +85,8 @@ constructor(public val role: String? = "user", public val parts: List<Part>) {
   }
 
   @OptIn(ExperimentalSerializationApi::class)
-  internal fun toInternal() = Internal(this.role ?: "user", this.parts.map { it.toInternal() })
+  internal fun toInternal(nullPartThought: Boolean = false) =
+    Internal(this.role ?: "user", this.parts.map { it.toInternal(nullPartThought) })
 
   @ExperimentalSerializationApi
   @Serializable

firebase-ai/src/main/kotlin/com/google/firebase/ai/type/Part.kt

@@ -337,13 +337,14 @@ internal object PartSerializer :
   }
 }
 
-internal fun Part.toInternal(): InternalPart {
+internal fun Part.toInternal(nullThought: Boolean): InternalPart {
+  val thought = if (nullThought) null else isThought
   return when (this) {
-    is TextPart -> TextPart.Internal(text, isThought, thoughtSignature)
+    is TextPart -> TextPart.Internal(text, thought, thoughtSignature)
     is ImagePart ->
       InlineDataPart.Internal(
         InlineData.Internal("image/jpeg", encodeBitmapToBase64Jpeg(image)),
-        isThought,
+        thought,
         thoughtSignature
       )
     is InlineDataPart ->
@@ -352,37 +353,37 @@ internal fun Part.toInternal(): InternalPart {
           mimeType,
           android.util.Base64.encodeToString(inlineData, BASE_64_FLAGS)
         ),
-        isThought,
+        thought,
         thoughtSignature
       )
     is FunctionCallPart ->
       FunctionCallPart.Internal(
         FunctionCallPart.Internal.FunctionCall(name, args, id),
-        isThought,
+        thought,
         thoughtSignature
       )
     is FunctionResponsePart ->
       FunctionResponsePart.Internal(
         FunctionResponsePart.Internal.FunctionResponse(name, response, id),
-        isThought,
+        thought,
         thoughtSignature
       )
     is FileDataPart ->
       FileDataPart.Internal(
         FileDataPart.Internal.FileData(mimeType = mimeType, fileUri = uri),
-        isThought,
+        thought,
         thoughtSignature
       )
     is ExecutableCodePart ->
       ExecutableCodePart.Internal(
         ExecutableCodePart.Internal.ExecutableCode(language, code),
-        isThought,
+        thought,
         thoughtSignature
       )
     is CodeExecutionResultPart ->
       CodeExecutionResultPart.Internal(
         CodeExecutionResultPart.Internal.CodeExecutionResult(outcome, output),
-        isThought,
+        thought,
         thoughtSignature
       )
     else ->