In this package, you have a mix of GPL 2 source files, GPL 2+ source files, and LGPL 2.1+ source files, with cmake/FindGraphviz.cmake having an interesting header: "Under the terms of Contract DE-AC04-94AL85000 with Sandia Coroporation, the U.S. Government retains certain rights in this software." This certainly doesn't seem standard. Additionally, in a lot of the source files, it states what the license is, then what the license was previously. This makes it really unclear for software distributors such as Debian who need to have clear and explicit copyright declarations. Please fix this.
- The KDE Licensing Policy (https://community.kde.org/Policies/Licensing_Policy p4/p5) lists what licenses can be used for application source files. Several source files are GPLv2-only, which is not an option there, they should be v2-or-later or v3-or-later. - The KDE Licensing Policy (p13) says CMake modules should be BSD-licensed, but FindGraphviz.cmake is LGPL2.1+. - org.kde.kgraphviewer.appdata.xml says the app is GPL-2.0+, which isn't true, since many source files don't have "or later". - Some source files have "Copyright Gael de Chalendar, GPLv2", and another paragraph saying "Copyright Jarosław Staniek, LGPL2 or later". I think there should be just one comment header with both copyright lines, and no mention of LGPL (relicensing LGPL2+ to GPL2 is possible and it's unnecessary to say what the license used to be). - While I don't know if it's legally required, some people seem to have done significant (copyrightable) contributions and aren't listed in the copyright comment lines.