Pointless cast warning

_[Original issue](https://code.google.com/p/error-prone/issues/detail?id=94) created by **drichter@google.com** on 2013-02-26 at 08:59 PM_

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Casts degrade program readability, and ones that are not automatically removed by the JRE hurt performance.

Here's an example extracted from real code:

class A {}
class B : A {}

List<B> someList;

for (A a : someList) // Line 1
{ ... ((B)a) ... } // Line 2

Line 2 should trigger the warning, citing the needless up-cast on Line 1.