Add workaround for connection timeouts

.ci/README.md

@@ -18,3 +18,14 @@ for a ssh key, which is used to copy files to sourceforge.
 
     gpg --batch --symmetric --cipher-algo AES256 --passphrase="$PMD_CI_SECRET_PASSPHRASE" file.txt
 
+## Known Issues
+
+Intermittent build failures while downloading dependencies from maven central.
+Root issue seems to be SNAT configs in Azure, which closes long running TCP connections
+only on one side: https://docs.microsoft.com/en-us/azure/load-balancer/troubleshoot-outbound-connection#idletimeout
+The default timeout is 4 minutes.
+
+Workaround as described in https://github.com/actions/virtual-environments/issues/1499 and
+https://issues.apache.org/jira/browse/WAGON-545 is applied:
+
+`-Dmaven.wagon.httpconnectionManager.ttlSeconds=180 -Dmaven.wagon.http.retryHandler.count=3`

.ci/build.sh

@@ -37,7 +37,6 @@ function pmd_ci_build_get_pom_version() {
 
 function pmd_ci_build_setup_maven() {
     # configure maven
-    echo "MAVEN_OPTS='-Xms1g -Xmx1g'" > ${HOME}/.mavenrc
     mkdir -p ${HOME}/.m2
     cp .ci/maven-settings.xml ${HOME}/.m2/settings.xml
 }
@@ -65,7 +64,7 @@ function pmd_ci_build_setup_oraclejdk7() {
 }
 
 function pmd_ci_build_run() {
-    MVN_BUILD_FLAGS="-B -V  -Djava7.home=${HOME}/oraclejdk7"
+    MVN_BUILD_FLAGS="-e -Dmaven.wagon.httpconnectionManager.ttlSeconds=180 -Dmaven.wagon.http.retryHandler.count=3 -V  -Djava7.home=${HOME}/oraclejdk7"
 
     log_info "This is a snapshot build"
     ./mvnw deploy -Possrh,sign $MVN_BUILD_FLAGS

.github/workflows/pull-requests.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Build with mvnw
         run: |
           source ${HOME}/java.env
-          ./mvnw -V clean install
+          ./mvnw -e -Dmaven.wagon.httpconnectionManager.ttlSeconds=180 -Dmaven.wagon.http.retryHandler.count=3 -V clean install
         shell: bash
       - name: Execute Danger
         if: ${{ runner.os ==  'Linux' }}