Allow maven central sync to run several times

Update the "sync to maven central" CI job so that it can be rerun if
necessary. We now first check if artifacts are already published before
triggering the sync from Bintray.

Closes gh-16866

ci/scripts/sync-to-maven-central.sh

@@ -7,6 +7,18 @@ groupId=$( cat artifactory-repo/build-info.json | jq -r '.buildInfo.modules[0].i
 version=$( cat artifactory-repo/build-info.json | jq -r '.buildInfo.modules[0].id' | sed 's/.*:.*:\(.*\)/\1/' )
 
 echo "Syncing ${buildName}/${buildNumber} to Maven Central"
+
+	publishStatus=$(curl \
+			-s \
+			-o /dev/null \
+			-I \
+			-w "%{http_code}"
+			"https://oss.sonatype.org/service/local/repositories/releases/content/org/springframework/boot/spring-boot/${version}/spring-boot-${version}.jar.sha1")
+
+	if [ ${publishStatus} == "200" ]; then
+		echo "Already published to Sonatype"
+	else
+		echo "Calling Bintray to sync to Sonatype"
 		curl \
 				-s \
 				--connect-timeout 240 \
@@ -16,5 +28,7 @@ echo "Syncing ${buildName}/${buildNumber} to Maven Central"
 				-f \
 				-X \
 				POST "https://api.bintray.com/maven_central_sync/${BINTRAY_SUBJECT}/${BINTRAY_REPO}/${groupId}/versions/${version}" > /dev/null || { echo "Failed to sync" >&2; exit 1; }
+	fi
+
 echo "Sync complete"
 echo $version > version/version