Rename event to payload

Author: daymxn

FirebaseAI/Sources/Types/Public/Live/LiveServerMessage.swift

@@ -19,7 +19,7 @@ public struct LiveServerMessage: Sendable {
   let serverMessage: BidiGenerateContentServerMessage
 
   /// The type of message sent from the server.
-  public enum Event: Sendable {
+  public enum Payload: Sendable {
     /// Content generated by the model in response to client messages.
     case content(LiveServerContent)
 
@@ -35,7 +35,7 @@ public struct LiveServerMessage: Sendable {
   }
 
   /// The message sent from the server.
-  public let payload: Event
+  public let payload: Payload
 
   /// Metadata on the usage of the cached content.
   public var usageMetadata: GenerateContentResponse.UsageMetadata? { serverMessage.usageMetadata }
@@ -47,7 +47,7 @@ public struct LiveServerMessage: Sendable {
 @available(watchOS, unavailable)
 extension LiveServerMessage {
   init?(from serverMessage: BidiGenerateContentServerMessage) {
-    guard let payload = LiveServerMessage.Event(from: serverMessage.messageType) else {
+    guard let payload = LiveServerMessage.Payload(from: serverMessage.messageType) else {
       return nil
     }
 
@@ -58,7 +58,7 @@ extension LiveServerMessage {
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, *)
 @available(watchOS, unavailable)
-extension LiveServerMessage.Event {
+extension LiveServerMessage.Payload {
   init?(from serverMessage: BidiGenerateContentServerMessage.MessageType) {
     switch serverMessage {
     case .setupComplete: