Fundamental lemma for the Jacquet–Rallis transfer

Suppose $E/F$ is an unramified quadratic extension, with rings of integers $O_E$ and $O_F$, and let $p$ be the residue characteristic of $F$. Set $V=F^n$ and let $1_{\mathfrak{k}}$ be the characteristic function of $M_n(O_F)\times O_F^n\times O_F^n\subset\mathfrak{gl}(V)\times V\times V^*$. Let $W_0=E^n$ with the split Hermitian form whose matrix is the anti-diagonal matrix $H$ with all entries equal to $1$, and let $1_{\mathfrak{k}_0}$ be the characteristic function of $\mathfrak{u}(W_0)(O_E)\times O_E^n$.

Fundamental lemma. When $p$ is odd, $1_{\mathfrak{k}}$ and $\{1_{\mathfrak{k}_0},0\}$ are transfers.

This is the fundamental lemma in the Jacquet–Rallis setting. The supplied status evidence says that it was proved in positive characteristic by Z. Yun and extended to characteristic zero by J. Gordon, so the claim is solved.