Upgrades for 1.0.0-SNAPSHOT

Version 1.0.0-SNAPSHOT has been created. It lifts the minimum Java version from 11 to 21.

Along with that, we should check the following possible dependency upgrades:

(not yet evaluated)

as of now: NONE

Evaluated and dropped:

[INFO]   org.eclipse.jdt:ecj ......................................................................... 3.43.0 -> 3.44.0 (known issues)
[INFO]   org.jsoup:jsoup ............................................................................. 1.19.1 -> 1.21.2 (transitive dep of maven-plugin-tools-generators 3.15.2 (latest non-milestone rel))

PRs:

[INFO]   com.diffplug.spotless:spotless-maven-plugin ............................................... 2.46.1 -> 3.1.0
[INFO]   ${spotless.version} ......................................................................... 2.46.1 -> 3.1.0
[INFO]   com.puppycrawl.tools:checkstyle ............................................................ 10.26.1 -> 12.3.0
[INFO]   net.sourceforge.pmd:pmd-java ................................................................ 7.18.0 -> 7.19.0
[INFO]   net.sourceforge.pmd:pmd-test ................................................................ 7.18.0 -> 7.19.0
[INFO]   net.sourceforge.pmd:pmd-xml ................................................................. 7.18.0 -> 7.19.0
[INFO]   org.hamcrest:hamcrest-library ..................................................................... 2.2 -> 3.0
[INFO]   ${junit.version} ............................................................................ 5.11.4 -> 6.0.1
[INFO]   ${mockito.version} ......................................................................... 4.10.0 -> 5.21.0
[INFO]   ch.qos.logback:logback-classic .............................................................. 1.2.13 -> 1.5.23
[INFO]   javax.xml.bind:jaxb-api .......................................................... 2.3.1 -> 2.4.0-b180830.0359
[INFO]   org.eclipse.jdt:org.eclipse.jdt.annotation ................................................ 2.3.100 -> 2.4.100
[INFO]   org.glassfish.jaxb:jaxb-runtime ............................................................... 2.3.1 -> 4.0.6
[INFO]   org.junit.jupiter:junit-jupiter-api .......................................................... 5.11.4 -> 6.0.1
[INFO]   org.junit.jupiter:junit-jupiter-params ....................................................... 5.11.4 -> 6.0.1
[INFO]   org.mockito:mockito-core .................................................................... 4.10.0 -> 5.21.0
[INFO]   org.mockito:mockito-junit-jupiter ........................................................... 4.10.0 -> 5.21.0
[INFO]   org.slf4j:slf4j-api ......................................................................... 1.7.36 -> 2.0.17

No files or tests are named; start by locating the Maven dependency configuration for the listed plugins and libraries. Review the evaluated, dropped, and PR upgrade lists, then establish which remaining upgrades are compatible with Java 21 and verify the resulting build and tests.