[maven-release-plugin] prepare release xwiki-platform-16.4.2

...xwiki-platform-attachment-picker-test-pageobjects/pom.xml

...chment-picker/xwiki-platform-attachment-picker-ui/pom.xml

...nt-picker/xwiki-platform-attachment-picker-webjar/pom.xml

...latform-attachment/xwiki-platform-attachment-test/pom.xml

...chment-test/xwiki-platform-attachment-test-docker/pom.xml

...t-test/xwiki-platform-attachment-test-pageobjects/pom.xml

...-platform-attachment/xwiki-platform-attachment-ui/pom.xml

...m-attachment/xwiki-platform-attachment-validation/pom.xml

...lidation/xwiki-platform-attachment-validation-api/pom.xml

...tion/xwiki-platform-attachment-validation-default/pom.xml

...idation/xwiki-platform-attachment-validation-test/pom.xml

.../xwiki-platform-attachment-validation-test-docker/pom.xml

...i-platform-attachment-validation-test-pageobjects/pom.xml

...alidation/xwiki-platform-attachment-validation-ui/pom.xml

xwiki-platform-core/xwiki-platform-bridge/pom.xml

xwiki-platform-core/xwiki-platform-captcha/pom.xml

...xwiki-platform-captcha/xwiki-platform-captcha-api/pom.xml

...i-platform-captcha/xwiki-platform-captcha-default/pom.xml

...-platform-captcha/xwiki-platform-captcha-jcaptcha/pom.xml

...tcha-jcaptcha/xwiki-platform-captcha-jcaptcha-api/pom.xml