Oracle acquired and then supported Hudson Continuous Integration through 2016. Oracle no longer updates or supports Hudson. It was available free and open source under an MIT license, but it is no longer being developed, and is no longer available.
Oracle CI in terms of setup lags behind all above products, but then its use is also limited to release management so we can't really compare. Majority of organizations have dedicated team to help with CI Process so they take care of managing all jobs and setup.