Preheat your oven to 350F. Line the bottom of a 9-inch springform cake pan with parchment paper and lightly oil the sides.
Place the cherries, walnuts, and sugar in the bottom of the cake pan.
In a large bowl, whisk together the flours, baking soda and powder, and salt. In a medium sized bowl, whisk together the oil, water, maple syrup, and vanilla extract. Pour the wet ingredients into the dry ingredients and stir until they're just combined (a few clumps is OK). Pour the cake batter over the cherries and walnuts.
Transfer the cake pan to the oven. Bake for 40 minutes, or until the cake is golden and the top is firm and set. Allow the cake to cool for an hour before releasing it from the springform pan and using a plate or platter to invert it. Slice and serve.