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* update gitignore .checkstyle files are being tracked which should not be * NOSONAR for statement excluded from SONAR analysis as it is already dealt using functional approach https://sonarcloud.io/project/issues?id=iluwatar_java-design-patterns&issues=AW8FwRBhm8eoEVQR-x0f&open=AW8FwRBhm8eoEVQR-x0f * achieved thread safety with lazy initialization https://sonarcloud.io/project/issues?fileUuids=AXb6t0PKusn4P8Tm-LmM&id=iluwatar_java-design-patterns&open=AXb6t19yusn4P8Tm-Lmo&resolved=false * remove double checked locking and initialize before using https://sonarcloud.io/project/issues?fileUuids=AXb6t0PKusn4P8Tm-LmK&id=iluwatar_java-design-patterns&open=AXb6t19qusn4P8Tm-Lmk&resolved=false * NOSONAR for the line https://sonarcloud.io/project/issues?id=iluwatar_java-design-patterns&issues=AXPd3iSe46HRSze7cz3D&open=AXPd3iSe46HRSze7cz3D Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>