A question about licensing...
The licensecheck tool gives the following result after filtering out the "UNKNOWN" reults:
COPYING: GNU Lesser General Public License, Version 3
LICENCE: GNU Lesser General Public License, Version 3
python/pyHepMC3.egg-info.in: *No copyright* CNRI Python License GNU General Public License, Version 3
python/pyHepMC3.protobufIO.egg-info.in: *No copyright* CNRI Python License GNU General Public License, Version 3
python/pyHepMC3.rootIO.egg-info.in: *No copyright* CNRI Python License GNU General Public License, Version 3
python/pyHepMC3.search.egg-info.in: *No copyright* CNRI Python License GNU General Public License, Version 3
include/HepMC3/LHEF.h: GNU General Public License, Version 2
python/include/LICENSE: BSD 3-Clause License
include/HepMC3/bxzstr/LICENSE: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/bxzstr.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/bz_stream_wrapper.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/compression_types.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/lzma_stream_wrapper.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/stream_wrapper.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/strict_fstream.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/z_stream_wrapper.hpp: *No copyright* Mozilla Public License 2.0
include/HepMC3/bxzstr/zstd_stream_wrapper.hpp: *No copyright* Mozilla Public License 2.0
examples/ViewerExample/cmake/Modules/FindGraphviz.cmake: GNU General Public License, Version 3
The main license was recently changed from GPLv3+ to LGPLv3+ That the egg-info files still say GPLv3 is probably a mistake.
The tricky bit is include/HepMC3/LHEF.h. This file says "The code is licenced under version 2 of the GPL", note without the "or any later version", so this is GPLv2 only. GPLv2 is not compatible with GPLv3, LGPLv3 or Apache-2.0. If this would have been GPLv2 or any later version, one could choose to use it under GPLv3. GPLv3 is compatible with LGPLv3 and Apache-2.0. The combined work would then be GPLv3 since it is the most resrictive licence. The problem is not caused by the change from GPLv3+ to LGPLv3+, since GPLv2 only was already incompatible with GPLv3 or later.
Is there a newer released version of the LHEF.h with an updated license?