JSONValue isn't documented to support the "in" operator. The source code apparently reveals that it does. Since normal people believe the documentation and don't automatically go to the source code first, it looks to all the world like this rather essential feature isn't there. Please document this.
Commit pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/e60c9dcf18b1b42d3b131840f975f1588ce6761d Merge pull request #3857 from BBasile/issue-15336 fix issue 15336, opIn undocumented for JSONValue
Commit pushed to stable at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/e60c9dcf18b1b42d3b131840f975f1588ce6761d Merge pull request #3857 from BBasile/issue-15336