Default layout has the following properties:
- :source maps to the ‘src’ directory.
- Anything under :source maps verbatim (e.g. :source, :main becomes
‘src/main’)
- :target maps to the ‘target’ directory.
- :target, :main maps to the ‘target’ directory as well.
- Anything under :target, :main maps verbatim (e.g. :target, :main, :classes
becomes ‘target/classes’)
- Anything else under :target also maps verbatim (e.g. :target, :test becomes
‘target/test’)