RFR: cleanup - removed unneeded casts in jdi

[Alan Bateman]

On 22/12/2017 21:06, David Holmes wrote:
> :
>
> The existing code is somewhat suspect as the Location interface 
> implements Comparable but it does not specify what it means to compare 
> two Locations! That's a bug in itself. LocationImpl has decided how to 
> compare two LocaltionImp's (but doesn't even check they are in the 
> same VirtualMachine!). Can we generalize that to accommodate other 
> Location implementations? Your change allows for this to happen, but 
> it will only work as expected if the other Location implementations 
> use the same comparison basis as LocationImpl - which is unspecified.
I'm also wondering about the change to validateMirrors and this 
assertion in the Mirror API:

"Any method on a Mirror that takes a Mirror as an parameter directly or 
indirectly (e.g., as a element in a List) will throw VMMismatchException 
if the mirrors are from different virtual machines."

There is an assumption in the implementation that two Mirror objects to 
the same VM will be the same implementation type.

-Alan