### Question:
CommonsMathWrapper { public static DoubleMatrix unwrap(RealMatrix x) { ArgChecker.notNull(x, "x"); return DoubleMatrix.ofUnsafe(x.getData()); } private  CommonsMathWrapper(); static UnivariateFunction wrapUnivariate(Function<Double, Double> f); static RealMatrix wrap(DoubleMatrix x); static RealMatrix wrapAsMatrix(DoubleArray x); static DoubleMatrix unwrap(RealMatrix x); static RealVector wrap(DoubleArray x); static DoubleArray unwrap(RealVector x);  }### Answer:
@Test public void testNullVector() { assertThatIllegalArgumentException() .isThrownBy(() -> CommonsMathWrapper.unwrap((RealVector) null)); }
@Test public void testNullRealMatrix() { assertThatIllegalArgumentException() .isThrownBy(() -> CommonsMathWrapper.unwrap((RealMatrix) null)); }