[maven-release-plugin] copy for tag checkstyle-6.8.1

[maven-release-plugin] copy for tag checkstyle-6.8

[maven-release-plugin] copy for tag checkstyle-6.7

[maven-release-plugin] copy for tag checkstyle-6.6

[maven-release-plugin] copy for tag checkstyle-6.5

[maven-release-plugin] copy for tag checkstyle-6.4.1

[maven-release-plugin] copy for tag checkstyle-6.4

[maven-release-plugin] copy for tag checkstyle-6.3

[maven-release-plugin] copy for tag checkstyle-6.2

[maven-release-plugin] copy for tag checkstyle-6.1.1