mc_unpackers MUST run before unpackers - use `ExtraInputs`
To avoid errors of the kind
ERROR UnpackParticlesAndVertices:: Unpack('/Event/HLT2/pPhys/PP2MCPRelations'): missing destination '/Event/HLT2/MC/Particles'
To avoid errors of the kind
ERROR UnpackParticlesAndVertices:: Unpack('/Event/HLT2/pPhys/PP2MCPRelations'): missing destination '/Event/HLT2/MC/Particles'