Incorrect eigenvalues from ND4J decomposition

Question

I've found that ND4J is returning incorrect eigenvalues:

 double[][] array = new double[][]{{1, 2, 1}, {6, -1, 0}, {-1, -2, -1}};
 INDArray matrix = Nd4j.create(array);

 INDArray values = Eigen.symmetricGeneralizedEigenvalues(matrix);
 System.out.println(values);

 [-6.2408, -1.3996, 6.6403]

I also tried this with the same result:

INDArray values = Eigen.symmetricGeneralizedEigenvalues(matrix, Nd4j.eye(matrix.rows()));

The actual values are [-4.0, 0.0, 3.0]. I've verified this by hand and with Colt, JAMA and EJML libraries.

I took a closer look at the docs, and saw that the input matrix of symmetricGeneralizedEigenvalues is supposed to be symmetric, which this one is not. However, I cannot find any documentation for a method that accepts non-symmetric square matrices. I feel like I must be doing something wrong here. What am I missing?