fix: [vertexai] make a copy of the list in ChatSession.setHistory() (#10608)

PiperOrigin-RevId: 618209294 Co-authored-by: Jaycee Li <jayceeli@google.com>

Author: copybara-service[bot]

java-vertexai/google-cloud-vertexai/src/main/java/com/google/cloud/vertexai/generativeai/ChatSession.java

@@ -92,7 +92,7 @@ public ChatSession withSafetySettings(List<SafetySetting> safetySettings) {
  ChatSession rootChat = rootChatSession.orElse(this);
  ChatSession newChatSession =
  new ChatSession(model.withSafetySettings(safetySettings), Optional.of(rootChat));
- newChatSession.setHistory(history);
+ newChatSession.history = history;
  return newChatSession;
  }
 
@@ -106,7 +106,7 @@ public ChatSession withSafetySettings(List<SafetySetting> safetySettings) {
  public ChatSession withTools(List<Tool> tools) {
  ChatSession rootChat = rootChatSession.orElse(this);
  ChatSession newChatSession = new ChatSession(model.withTools(tools), Optional.of(rootChat));
- newChatSession.setHistory(history);
+ newChatSession.history = history;
  return newChatSession;
  }
 
@@ -253,7 +253,7 @@ private Optional<ResponseStream<GenerateContentResponse>> getCurrentResponseStre
 
  /** Set the history to a list of Content */
  public void setHistory(List<Content> history) {
- this.history = history;
+ this.history = new ArrayList<>(history);
  }
 
  /** Sets the current response of the root chat session (if exists) or the current chat session. */