[maven-release-plugin] copy for tag pmd_releases/6.15.0

[maven-release-plugin] copy for tag pmd_releases/6.14.0

[maven-release-plugin] copy for tag pmd_releases/6.13.0

[maven-release-plugin] copy for tag pmd_releases/6.12.0

[maven-release-plugin] copy for tag pmd_releases/6.11.0

[maven-release-plugin] copy for tag pmd_releases/6.10.0

[maven-release-plugin] copy for tag pmd_releases/6.9.0

[maven-release-plugin] copy for tag pmd_releases/6.8.0

[maven-release-plugin] copy for tag pmd_releases/6.7.0

[maven-release-plugin] copy for tag pmd_releases/6.6.0