remove unused imports
merge
Merge branch 'master' of https://github.com/maismail/stratosphere-workshop-template
Merge branch 'master' of https://github.com/maismail/stratosphere-workshop-template
Merge branch 'master' of https://github.com/maismail/stratosphere-workshop-template.git
tree building
Merge branch 'master' of https://github.com/maismail/stratosphere-workshop-template