Missing type checks when using polymorphic type ids

[cowtowncoder]

(report by Lukes Euler)

JavaType supports limited amount of generic typing for textual representation, originally just to support typing needed for EnumMap (I think). Based on some reports, it appears that some of type compatibility checks are not performed in those cases; if so, they should be made since there is potential for abuse.
The problem here although actual type assignment will fail later on, ability to trigger some of processing (instantiation of incompatible classes, perhaps assingnment of properties) may itself be vulnerability.

[cowtowncoder]

Fixed in 2.8.10 / 2.9.1