[Tex/LaTex] Custom area legend image not working

legendpgfplotstikz-pgf

I'm trying to use the result from a fill between as a legend entry, but I can't get it to work:

\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}

\usepgfplotslibrary{fillbetween}

\begin{document}

\begin{figure}
    \begin{tikzpicture}
        \begin{axis}
            \addplot[name path = upper, draw = none] {5 + rand};
            \addplot[name path = lower, draw = none] {-5 + rand};
            \addplot[black!10, area legend] fill between[of = upper and lower];
            \addlegendentry{My interval}
        \end{axis}
    \end{tikzpicture}
\end{figure}

\end{document}

gives

enter image description here

with a line in the legend image instead of the rectangle I expected from using area legend in the options to \addplot.

I tried providing a legend image manually using

\addlegendimage{\draw[fill = black!10] (0cm, -0.1cm) rectangle (0.6cm, 0.1cm)}

but that did nothing. (The \draw code is inspired by Section 4.9.5 in the pgfplots manual and is supposed to be the default appearance of a area legend entry.)

Any ideas? Thanks in advance.

Edit:

Adding area legend to the axis option gets me halfway there, but the fill is still not right.

enter image description here

Best Answer

The comment by John Kormylo put me on the right track. The key is to make the legend refer to the third plot only by issuing forget plot to the two previous ones. The following works:

\begin{axis}
    \addplot[name path = upper, draw = none, forget plot] {5 + rand};
    \addplot[name path = lower, draw = none, forget plot] {-5 + rand};
    \addplot[fill = black!10, area legend] fill between[of = upper and lower];
    \addlegendentry{My interval}
\end{axis}

enter image description here

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