FunctionCallbackWrapper has a Builder object to build FunctionCallbackWrappers. The Builder has a method withObjectMapper to pass in custom ObjectMappers. However, this custom ObjectMapper is not used in the constructor of FunctionCallbackWrapper, so FunctionCallbackWrapper always uses the default ObjectMapper.
new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
This causes problems when using Kotlin data classes as the function types. For serialization/deserialization with Kotlin data classes, the KotlinModule should be registered to the ObjectMapper, which requires a custom ObjectMapper. The workaround is using records.
In this fix, I added the ObjectMapper to the constructor of FunctionCallbackWrapper. No null-check is required as this constructor is private and Builder is the only way to create new instances of FunctionCallbackWrapper. Null-check is already done in the build method of Builder. The default value of ObjectMapper is the same as before, which is also already defined in Builder.
Comment From: tzolov
Thanks for the improvement @alexcheng1982
Comment From: tzolov
Rebased, squashed and merged at 0a3a2022a85eca12023c2c844ec0470fc78c1da7
in addition to the original commit make the default object mapper match the config of the ModelOptionsUtil.