CheckstyleNoHttp fails on builds executed without clean task

[vpavic]

Running project build fails with checkstyleNohttp task error if not cleaned beforehand.

This is apparently caused by the following symlinks:

• spring-session-docs/modules/ROOT/examples/spring-session-data-mongodb-dir
• spring-session-docs/modules/ROOT/examples/spring-session-samples

As the symlink targets are the root directories of spring-session-data-mongodb and all sample modules, they will inevitably pick up their respective build directories once created by building the project.