Say one has an extended leave of absence from the workforce as a software engineer. During that time, over a period of time, one makes a series of non-trivial contributions to an open-source project, as they wish to keep their skills current.
As there would otherwise be a significant gap between the most recent employer and the current time, is it suitable and appropriate to list it in the "Experience" section alongside past paid employers, so long as the experience is not mis-construed? Would an employer find it misleading? Should it instead be relegated to a "hobbies" section later in the resume? How can it best be presented to be both truthful and flattering to the person submitting the resume?