Add whitespace
Update javadoc
Fix [SonarQube] Synchronized class Vector should not be used (Replace
the synchronized class "Vector" by an unsynchronized one such as
"ArrayList" or "LinkedList")

Fix [SonarQube] Loose Coupling (Avoid using implementation types like
'ArrayList'; use the interface instead)
Remove unused import
Fix [SonarQube] Synchronized class Vector should not be used (Replace
the synchronized class "Vector" by an unsynchronized one such as
"ArrayList" or "LinkedList")

Fix [SonarQube] Loose Coupling (Avoid using implementation types like
'ArrayList'; use the interface instead)