The primitive homology conjecture for closed exact Lagrangians

Let $M$ be a Weinstein manifold of dimension $2n$, and let $L\subset M$ be a closed exact Lagrangian submanifold with vanishing Maslov class. Its homology class is $[L]\in H_n(M;\mathbb{Z})$. Primitive homology conjecture. The class $[L]$ is primitive. This conjecture concerns a basic obstruction to closed exact Lagrangians in Weinstein manifolds; the source presents it as a conjecture and does not state a resolution.