[Bug]:在结构化输出时，总是输出失败，提示报错信息为No structured output in message metadata. Key '_structured_output' not found

The abnormal information is：
java.util.concurrent.CompletionException: java.lang.IllegalStateException: No structured output in message metadata. Key '_structured_output' not found.
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315) ~[na:na]
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320) ~[na:na]
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run$$$capture(CompletableFuture.java:1770) ~[na:na]
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java) ~[na:na]
at java.base/java.util.concurrent.ThreadPerTaskExecutor$TaskRunner.run(ThreadPerTaskExecutor.java:314) ~[na:na]
at java.base/java.lang.VirtualThread.run(VirtualThread.java:329) ~[na:na]

The general reason is that the tool was not called, but the specific reason is still unclear

The text information returned by Ai is：There is no format here, all are the original information returned by Ai
```json
{
"error": "",
"issueDate": "2020-07-10",
"roadTrafficSn": "11231220",
"validityPeriod": "",
"vehicleNum": "蒙123123"
}
```
OR

{"error": "", "vehicleNum": "鲁H12312", "vehicleNumColor": "黄色"}

The framework I use is springboot, and I have encountered similar issues with pure Java code before, mainly with structured tools