Try downloading an artifact via curl.

Author: tecarter94

deploy/tasks/buildah-oci-ta.yaml

@@ -398,7 +398,7 @@ spec:
             echo ${DOMAIN_PROXY_ARGS[@]} # TODO remove
             /app/domain-proxy-server-runner &
             server_pid=$!
-            curl -I ${CACHE_URL}
+            curl -v "${CACHE_URL}/org/apache/maven/plugins/maven-jar-plugin/3.4.1/maven-jar-plugin-3.4.1.jar"
           fi
         fi
 

java-components/build-request-processor/src/main/java/com/redhat/hacbs/container/build/preprocessor/AbstractPreprocessor.java

@@ -104,7 +104,7 @@ public void run() {
             # useful if Gradle/Ant also requires Maven configured.
             export MAVEN_HOME=${MAVEN_HOME:=/opt/maven/3.8.8}
             export GRADLE_USER_HOME="${JBS_WORKDIR}/software/settings/.gradle"
-            curl -I ${PROXY_URL}
+            curl -v "${CACHE_URL}/org/apache/maven/plugins/maven-jar-plugin/3.4.1/maven-jar-plugin-3.4.1.jar"
 
             mkdir -p ${JBS_WORKDIR}/logs ${JBS_WORKDIR}/packages ${JBS_WORKDIR}/settings ${HOME}/.sbt/1.0 ${GRADLE_USER_HOME} ${HOME}/.m2
             cd ${JBS_WORKDIR}/source