Added some comments [skip CI]
Added some comments [skip CI]


Former-commit-id: ccac56d3fe1e7c0ac4be86c9f2c681ee0e0ecf81 [formerly eb4fadd2cfaa1e9648a8af57bf286b57e2e8f335]
Former-commit-id: 011b1b86797c71392ebbb86696ba2770151aacc4
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine