Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit bd462b5dcd59b8000cb7aa9b43daf36fe1400c4b.
Revert "[maven-release-plugin] prepare release 6.2.1"

This reverts commit 76e0b8acf04ba3375a7160d0bb666e5faaefb99c.
[maven-release-plugin] prepare release 6.2.1
[maven-release-plugin] prepare for next development iteration