Git resolve composer conflicts. Source: http://blog.doh.ms/2016/11/28/solving-conflicts-in-composer-lock/
> Terminal 1
git diff HEAD MERGE_HEAD -- composer.json
> Terminal 2
git checkout origin/develop -- composer.lock
git checkout origin/develop -- composer.json
composer require drupal/migrate_plus:^4.0@beta --update-with-dependencies
composer update drupal/migrate_tools:^4.0@beta