Spring AI ModelOptionsUtils.merge() fails with DefaultToolCallingChatOptions due to missing @JsonProperty annotations

Bug description When using ModelOptionsUtils.merge(runtimeOptions, this.defaultOptions, DefaultToolCallingChatOptions.class), an exception is thrown:

IllegalArgumentException: No @JsonProperty fields found in the org.springframework.ai.chat.tool.DefaultToolCallingChatOptions

The root cause is that ModelOptionsUtils scans for @JsonProperty annotations on all option classes, but DefaultToolCallingChatOptions does not declare any such annotations. This mismatch causes the merge process to fail when using custom model integrations.

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Environment

Spring AI version: 1.0.1 (includes master branch)

Steps to reproduce Create a custom chat model implementation that uses DefaultToolCallingChatOptions as default options.

Call: ModelOptionsUtils.merge(runtimeOptions, this.defaultOptions, DefaultToolCallingChatOptions.class);

Observe the exception.

Since it is default, then when I want to integrate the model into spring-ai myself, I don't want to customize it, why don't I use the default? Otherwise, what is the meaning of providing a default implementation?