Allow building with QA on Java 17+

Running `mvn ... -Dqa` with Java 17/21 breaks errorprone.

Fixed with:

* Update errorProne.version:2.18.0 -> 2.24.1
* Add `geowebcache/.mvn/jvm.config` with the required `--add-exports`
for the `maven-compiler-plugin` as explained at https://errorprone.info/docs/installation#jdk-16.

geowebcache/.mvn/jvm.config

@@ -0,0 +1,10 @@
+--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

geowebcache/pom.xml

@@ -86,7 +86,7 @@
     <jackson.databind.version>2.15.2</jackson.databind.version>
     <jetty.version>9.4.33.v20201020</jetty.version>
     <errorProneFlags></errorProneFlags>
-    <errorProne.version>2.18.0</errorProne.version>
+    <errorProne.version>2.24.1</errorProne.version>
     <javac.version>9+181-r4173-1</javac.version>
     <pmd.version>6.55.0</pmd.version>
     <checkstyle.skip>false</checkstyle.skip>