Design principles of ConstantDesc.resolveConstantDesc

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Hello,
While looking at ConstantDesc.resolveConstantDesc, I find that user
code cannot call resolveConstantDesc without extra casts for these
types of constant descriptors: ClassDesc, MethodTypeDesc,
MethodHandleDesc. Other constant descriptors can have their constants
resolved without casts: Double, DynamicConstantDesc, Float, Integer,
Long, String.

This appears as a design flaw to me, as in the implementation of the 3
cast-required types, their return types are Class, MethodType, and
MethodHandle respectively. However, these implementations are not
visible to users, so they cannot be benefitted by the more specific
return types in the implementations (unlike the VarHandleDesc and
EnumDesc, which are public).

If this is valid, I propose to add covariant overrides to
resolveConstantDesc in the ClassDesc, MethodTypeDesc, and
MethodHandleDesc interfaces. These should have little backward
compatibility concerns as these interfaces are already sealed. I can
open an issue on JBS and submit a patch.

Chen Liang