List<MethodContract> (int argIndex, int argCount, boolean returnArg) { ValueConstraint[] constraints = createConstraintArray(argCount); constraints[argIndex] = NULL_VALUE; StandardMethodContract failContract = new StandardMethodContract(constraints, fail()); if (returnArg) { return Arrays.asList(failContract, StandardMethodContract.trivialContract(argCount, returnParameter(argIndex))); } return Collections.singletonList(failContract); }