class StreamingTextMessageContentBuilder extends MessageContentBuilder{
    private String text;
    private String streamId;
    private boolean generating;
    public static StreamingTextMessageContentBuilder newBuilder(String streamId) {
        StreamingTextMessageContentBuilder builder = new StreamingTextMessageContentBuilder();
        builder.generating = false;
        builder.streamId = streamId;
        return builder;
    }
    public StreamingTextMessageContentBuilder text(String text) {
        this.text = text;
        return this;
    }

    public StreamingTextMessageContentBuilder generating(boolean generating) {
        this.generating = generating;
        return this;
    }

    @Override
    public MessagePayload build() {<FILL_FUNCTION_BODY>}
}

        MessagePayload payload = encodeBase();
        payload.setSearchableContent(text);
        payload.setContent(streamId);
        if(generating) {
            //正在生成消息的类型是14，存储标记位为透传为4。
            payload.setType(14);
            payload.setPersistFlag(4);
        } else {
            //已经生成消息的类型是15，存储标记位为透传为3。
            payload.setType(15);
            payload.setPersistFlag(3);
        }
        return payload;
    
<methods>public non-sealed void <init>() ,public abstract cn.wildfirechat.pojos.MessagePayload build() ,public cn.wildfirechat.messagecontentbuilder.MessageContentBuilder extra(java.lang.String) ,public cn.wildfirechat.messagecontentbuilder.MessageContentBuilder mentionedTargets(List<java.lang.String>) ,public cn.wildfirechat.messagecontentbuilder.MessageContentBuilder mentionedType(int) <variables>private java.lang.String extra,private List<java.lang.String> mentionedTargets,private int mentionedType