Merge branch 'hotfix/update_gem_0.2.17' into develop

* hotfix/update_gem_0.2.17:
  update gem
gem updated
Merge branch 'hotfix/update_gem_0.2.19'

* hotfix/update_gem_0.2.19:
  gem updated
Merge branch 'hotfix/update_gem_0.2.19' into develop

* hotfix/update_gem_0.2.19:
  gem updated
Merge branch 'release/0.4.4'

* release/0.4.4: