A strange problem for tool calling

a same request ，run it， and it will become sometimes it's good, sometimes it's abnormal. The following are the abnormal information:

2025-05-19 19:24:57 ERROR o.s.a.m.o.ErrorLoggingObservationHandler - Traced Error:
java.lang.IllegalArgumentException: toolInput cannot be null or empty
at org.springframework.util.Assert.hasText(Assert.java:253)
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Assembly trace from producer [reactor.core.publisher.FluxDefer] :
reactor.core.publisher.Flux.defer(Flux.java:810)
org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$11(OpenAiChatModel.java:362)
Error has been observed at the following site(s):
*_______Flux.defer ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$11(OpenAiChatModel.java:362)
| Flux.subscribeOn ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$11(OpenAiChatModel.java:377)
*______Flux.flatMap ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$14(OpenAiChatModel.java:360)
Original Stack Trace:
at org.springframework.util.Assert.hasText(Assert.java:253)
at org.springframework.ai.tool.method.MethodToolCallback.call(MethodToolCallback.java:99)
at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCall(DefaultToolCallingManager.java:205)
at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCalls(DefaultToolCallingManager.java:128)
at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$10(OpenAiChatModel.java:365)
at reactor.core.publisher.FluxDefer.subscribe(FluxDefer.java:46)
at reactor.core.publisher.InternalFluxOperator.subscribe(InternalFluxOperator.java:68)
at reactor.core.publisher.FluxSubscribeOn$SubscribeOnSubscriber.run(FluxSubscribeOn.java:194)
at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:84)
at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:37)
at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
2025-05-19 19:24:57 ERROR o.s.ai.chat.model.MessageAggregator - Aggregation Error
java.lang.IllegalArgumentException: toolInput cannot be null or empty
at org.springframework.util.Assert.hasText(Assert.java:253)
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Assembly trace from producer [reactor.core.publisher.FluxDefer] :
reactor.core.publisher.Flux.defer(Flux.java:810)
org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$11(OpenAiChatModel.java:362)
Error has been observed at the following site(s):
*_________Flux.defer ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$11(OpenAiChatModel.java:362)
| Flux.subscribeOn ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$11(OpenAiChatModel.java:377)
*__Flux.flatMap ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$14(OpenAiChatModel.java:360)
| Flux.doOnError ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$14(OpenAiChatModel.java:383)
| Flux.doFinally ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$14(OpenAiChatModel.java:384)
| Flux.contextWrite ⇢ at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$14(OpenAiChatModel.java:385)
| Flux.doOnSubscribe ⇢ at org.springframework.ai.chat.model.MessageAggregator.aggregate(MessageAggregator.java:94)
| Flux.doOnNext ⇢ at org.springframework.ai.chat.model.MessageAggregator.aggregate(MessageAggregator.java:105)
| Flux.doOnComplete ⇢ at org.springframework.ai.chat.model.MessageAggregator.aggregate(MessageAggregator.java:144)
Original Stack Trace:
at org.springframework.util.Assert.hasText(Assert.java:253)
at org.springframework.ai.tool.method.MethodToolCallback.call(MethodToolCallback.java:99)
at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCall(DefaultToolCallingManager.java:205)
at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCalls(DefaultToolCallingManager.java:128)
at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$10(OpenAiChatModel.java:365)
at reactor.core.publisher.FluxDefer.subscribe(FluxDefer.java:46)
at reactor.core.publisher.InternalFluxOperator.subscribe(InternalFluxOperator.java:68)
at reactor.core.publisher.FluxSubscribeOn$SubscribeOnSubscriber.run(FluxSubscribeOn.java:194)
at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:84)
at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:37)
at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
2025-05-19 19:24:57 ERROR o.s.a.m.o.ErrorLoggingObservationHandler - Traced Error:
java.lang.IllegalArgumentException: toolInput cannot be null or empty

the code is simple below:

Start with OpenAiChatModel.java around lines 360-385 and trace the reported call through DefaultToolCallingManager and MethodToolCallback.java line 99. Reproduce the same tool-calling request repeatedly and determine why toolInput is sometimes null or empty; done means the reported request no longer produces this exception.