[maven-release-plugin] copy for tag v5.1.21

[maven-release-plugin] copy for tag v6.0.0.M4

[maven-release-plugin] copy for tag v6.0.0.M3

[maven-release-plugin] copy for tag v5.1.20

[maven-release-plugin] copy for tag v6.0.0.M2

[maven-release-plugin] copy for tag v5.1.19

[maven-release-plugin] copy for tag v6.0.0.M1

[maven-release-plugin] copy for tag v5.1.18

[maven-release-plugin] copy for tag v5.1.17

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