fix: Build producer_with_xml separately to avoid classloader conflict

The SCC Maven plugin with extensions=true causes a BasicAuthCache
ClassCastException when too many modules accumulate classrealms in a
single reactor build. Pre-resolving plugins doesn't help because the
issue is Maven's classrealm architecture, not JAR caching.

Fix: exclude producer_with_xml from the reactor and build it in its
own Maven invocation in runMavenBuilds.sh.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: marcingrzejszczak

.github/workflows/maven.yml

@@ -24,6 +24,5 @@ jobs:
     - name: Pre-resolve SCC plugin to avoid classloader conflict
       run: |
         cd common && ./mvnw dependency:resolve-plugins -B && cd ..
-        ./mvnw dependency:resolve-plugins -Ptest -B || true
     - name: Build with Maven
       run: ./scripts/runMavenBuilds.sh

pom.xml

@@ -131,7 +131,7 @@
 				<module>producer_with_webtestclient_restdocs</module>
 				<module>producer_with_dsl_restdocs</module>
 <!--				<module>producer_with_spock</module>--> <!-- TODO: Spock Spring is broken -->
-				<module>producer_with_xml</module>
+<!--				<module>producer_with_xml</module>--> <!-- Built separately: SCC plugin classloader conflict in reactor -->
 				<module>producer_with_latest_2_2_features</module>
 <!--				<module>producer_kotlin_ftw</module>--><!-- Kotlin issues -->
 				<module>producer_java</module>

scripts/runMavenBuilds.sh

@@ -36,6 +36,18 @@ function build_maven() {
     else
         ./mvnw clean install -Ptest -B
     fi
+
+    # Build producer_with_xml separately to avoid SCC plugin classloader
+    # conflict (BasicAuthCache ClassCastException) that occurs when too many
+    # modules with extensions=true accumulate classrealms in a single reactor.
+    echo -e "\n\nBuilding producer_with_xml separately\n\n"
+    cd ${ROOT}/producer_with_xml
+    if [[ "${SKIP_TESTS}" == "true" ]]; then
+        ./mvnw clean install -B -DskipTests -DfailIfNoTests=false -Dspring.cloud.contract.verifier.skip=true -Dspring.cloud.contract.verifier.jar.skip=true
+    else
+        ./mvnw clean install -B
+    fi
+    cd ${ROOT}
 }
 
 cat <<'EOF'