The numerical abundance conjecture for nef line bundles on projective Calabi–Yau manifolds

Let $X$ be a projective Calabi–Yau manifold, meaning a compact Kähler manifold with $c_1(K_X)=0$ in $H^{1,1}(X,\mathbb{R})$, and let $L\to X$ be a nef line bundle. Numerical abundance conjecture. Then $L$ is numerically semiample. This is known for surfaces but remains open already in dimension three.