Revert "Strip redundant serial names"

This reverts commit c75b68e.

Author: emilypgoogle

firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/type/FunctionCallingConfig.kt

@@ -49,7 +49,10 @@ internal constructor(
   }
 
   @Serializable
-  internal data class Internal(val mode: Mode, val allowedFunctionNames: List<String>? = null) {
+  internal data class Internal(
+    val mode: Mode,
+    @SerialName("allowed_function_names") val allowedFunctionNames: List<String>? = null
+  ) {
     @Serializable
     enum class Mode {
       @SerialName("MODE_UNSPECIFIED") UNSPECIFIED,

firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/type/GenerationConfig.kt

@@ -161,15 +161,15 @@ private constructor(
   @Serializable
   internal data class Internal(
     val temperature: Float?,
-    val topP: Float?,
-    val topK: Int?,
-    val candidateCount: Int?,
-    val maxOutputTokens: Int?,
-    val stopSequences: List<String>?,
-    val responseMimeType: String? = null,
-    val presencePenalty: Float? = null,
-    val frequencyPenalty: Float? = null,
-    val responseSchema: Schema.Internal? = null,
+    @SerialName("top_p") val topP: Float?,
+    @SerialName("top_k") val topK: Int?,
+    @SerialName("candidate_count") val candidateCount: Int?,
+    @SerialName("max_output_tokens") val maxOutputTokens: Int?,
+    @SerialName("stop_sequences") val stopSequences: List<String>?,
+    @SerialName("response_mime_type") val responseMimeType: String? = null,
+    @SerialName("presence_penalty") val presencePenalty: Float? = null,
+    @SerialName("frequency_penalty") val frequencyPenalty: Float? = null,
+    @SerialName("response_schema") val responseSchema: Schema.Internal? = null,
   )
 
   public companion object {

firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/type/ToolConfig.kt

@@ -16,6 +16,7 @@
 
 package com.google.firebase.vertexai.type
 
+import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 
 /**
@@ -41,5 +42,8 @@ public class ToolConfig(internal val functionCallingConfig: FunctionCallingConfi
     )
 
   @Serializable
-  internal data class Internal(val functionCallingConfig: FunctionCallingConfig.Internal?)
+  internal data class Internal(
+    @SerialName("function_calling_config")
+    val functionCallingConfig: FunctionCallingConfig.Internal?
+  )
 }