…ecover)

Run CI on a JDK 17/21/25 matrix (CircleCI 2.1 parameterized job). Bump
JaCoCo to 0.8.15, Mockito to 5.23.0 and System Stubs to 2.1.8 so the
suite instruments and runs on Java 25, and grant the configuration
environment-variable tests the required --add-opens.

Upgrades org.assertj:assertj-core from 3.24.2 to 3.27.7 so the test
suite's Byte Buddy-backed assertions run on the Java 25 build matrix,
and picks up the XXE fix in isXmlEqualTo (CVE-2026-24400).

Bump runtime dependencies (Gson 2.14.0, Guava 33.6.0-jre, SLF4J 2.0.18,
jackson-databind-nullable 0.2.10, swagger-annotations 1.6.16,
ThreeTen-Backport 1.7.3) and declare an explicit jsr305 dependency for
the JSR-305 annotations used by the generated models, which Guava no
longer brings in transitively.

Bump test dependencies (Logback 1.5.34, JSONassert 1.5.3, spring-test
6.1.21 to match spring-web) and drop the unused System Rules dependency.

Bump build plugins: maven-compiler-plugin 3.14.0, maven-surefire-plugin
3.5.6, maven-source-plugin 3.4.0, maven-javadoc-plugin 3.12.0,
versions-maven-plugin 2.18.0, maven-gpg-plugin 3.2.8 and
central-publishing-maven-plugin 0.10.0.