refactoring add @NonNull
refactoring add @NonNull
refactoring protected <- public
refactoring add SourceDirectory.of()
refactoring add Constraint.of()
refactoring add Violation.of()
refactoring add ExcludePackage.of()
refactoring add DefaultDependency.of()
refactoring Dependency.NULL use DefaultDependency
remove not use Dependency.NULL
remove not use PackageName.NULL
refactoring add PackageName.of()
refactoring remove interface needless public
extract ConstraintChecker.of()
extract ImportParser.of()