It seems as if the rosserial repository is licenced under a BSD-license. However, BSD is not a single licence but a whole collection of licences, with some being Open Source and others not being Open Source (according to the OSI). To make things easy, I recommend the BSD-2-Clause licence (https://spdx.org/licenses/BSD-2-Clause.html). Please add a proper licence file and update the package.xml files accordingly.
It seems as if the rosserial repository is licenced under a BSD-license. However, BSD is not a single licence but a whole collection of licences, with some being Open Source and others not being Open Source (according to the OSI). To make things easy, I recommend the BSD-2-Clause licence (https://spdx.org/licenses/BSD-2-Clause.html). Please add a proper licence file and update the package.xml files accordingly.