fastjson2将bean转String失败，同样的bean换成fastjson则转String正常

报错：java.lang.UnsupportedOperationException: can't load this type of class file

Start by reproducing the reported bean-to-String conversion failure in fastjson2 and capture the complete stack trace and bean definition. Compare the same bean conversion with fastjson, then identify the relevant serialization entry point. Done means the failure is explained and a focused regression test demonstrates the corrected behavior.

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