Looks like TypeUtil.getMethod is trying to load class (javassist/util/proxy/MethodHandler) from the current thread context classloader, and this class was not available in that classloader.
How was javassist/util/proxy/MethodHandler class packaged in your application? The thread context classloader might not be set with all the necessary classpaths here..
Can you try to drop this class under $AS_INSTALL/lib and see if the problem can be worked around?
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