Solve SpotBugs issue CT_CONSTRUCTOR_THROW in generated code

[mikir]

SpotBugs issue CT_CONSTRUCTOR_THROW (Be wary of letting constructors throw exceptions) in generated code has been filtered out. It would be better to fix generated code instead.

Example from language/choice_types tests:

CT 	Exception thrown in class choice_types.bitmask_param_choice.BitmaskParamChoice at new choice_types.bitmask_param_choice.BitmaskParamChoice(PackingContext, BitStreamReader, Selector)
        will leave the constructor. The object under construction remains partially initialized and may be vulnerable to Finalizer attacks.

Bug type CT_CONSTRUCTOR_THROW
In class choice_types.bitmask_param_choice.BitmaskParamChoice
In method new choice_types.bitmask_param_choice.BitmaskParamChoice(PackingContext, BitStreamReader, Selector)
At BitmaskParamChoice.java:[line 60]
At BitmaskParamChoice.java:[line 60]

Classes that throw exceptions in their constructors are vulnerable to Finalizer attacks. A finalizer attack can be prevented, by declaring the class final, using an empty finalizer declared as final, or by a clever use of a private constructor. See SEI CERT Rule OBJ-11 for more information.

[Mi-La]

All generated classes are now declared as final since they were never intended to be further extended by applications. This solution solves CT_CONSTRUCTOR_THROW SpotBugs warning.