Resolve violations of IDEA inspections 2020.1.1

[romani]

Violations: https://teamcity.jetbrains.com/buildConfiguration/Checkstyle_ContributionIdeaInspectionsPullRequest/3854536?buildTab=Inspection

Java/Abstraction issues 'public' method with 'boolean' parameter (Errors) (1) Java/Code maturity Deprecated API usage (Errors) (1) Use of System.out or System.err (Errors) (7) Java/JUnit JUnit test method without any assertions (Errors) (25) Java/Naming conventions/Method Method naming convention (Errors) (1) Java/Performance StringBuilder without initial capacity (Errors) (1) Java/Portability Call to 'System.exit()' or related methods (Errors) (1) Java/Probable bugs Use of Properties object as a Hashtable (Errors) (6) Java/Resource management AutoCloseable used without 'try'-with-resources (Errors) (7) I/O resource opened but not safely closed (4) Java/Verbose or redundant code constructs Stream API call chain can be simplified (2)