Confluence Source Distribution fails to build due to missing Team Calendars dependency

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-dependency-plugin:2.8:copy (download-tc-obr) on project confluence-webapp: Unable to find artifact. Could not find artifact com.atlassian.confluence.extra.team-calendars:team-calendars:obr:5.2.13 in atlassian-proxy (https://m2proxy.atlassian.com/repository/public)
[ERROR]
[ERROR] Try downloading the file manually from the project website.
[ERROR]
[ERROR] Then, install it using the command:
[ERROR] mvn install:install-file -DgroupId=com.atlassian.confluence.extra.team-calendars -DartifactId=team-calendars -Dversion=5.2.13 -Dpackaging=obr -Dfile=/path/to/file
[ERROR]
[ERROR] Alternatively, if you host your own repository you can deploy the file there:
[ERROR] mvn deploy:deploy-file -DgroupId=com.atlassian.confluence.extra.team-calendars -DartifactId=team-calendars -Dversion=5.2.13 -Dpackaging=obr -Dfile=/path/to/file -Durl=[url] -DrepositoryId=[id]
[ERROR]
[ERROR]
[ERROR] com.atlassian.confluence.extra.team-calendars:team-calendars:obr:5.2.13

 <execution>
                        <id>download-tc-obr</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>copy</goal>
                        </goals>
                        <configuration>
                            <artifactItems>
                                <artifactItem>
                                    <groupId>com.atlassian.confluence.extra.team-calendars</groupId>
                                    <artifactId>team-calendars</artifactId>
                                    <version>${bundled.team-calendar.version}</version>
                                    <type>obr</type>
                                    <overWrite>true</overWrite>
                                    <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/others</outputDirectory>
                                </artifactItem>
                            </artifactItems>
                        </configuration>
                    </execution>