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This malicious BigInteger class is clearly mutable, thanks to the setValue() method. Furthermore, the modPow() method is subject to precision loss (see NUM00-J. Ensure that integer operations do not result in Detect or prevent integer overflow, NUM11-J. Check floating point inputs for exceptional values, NUM15-J. Ensure conversions of numeric types to narrower types do not result in lost or misinterpreted data and NUM17-J. Beware of precision loss when converting primitive integers to floating-point for more info). Any code that receives an object of this class, and assumes it is imutable will have unexpected behavior. (The BigInteger.modPow() method has several useful cryptographic applications.)
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