Build failed in Jenkins: java-idp-tomcat-base-9.0 #6

[Shibboleth Jenkins]

See <http://127.0.0.1:1583/jenkins/job/java-idp-tomcat-base-9.0/6/display/redirect>

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Started by upstream project "java-parent-project-v7" build number 122
originally caused by:
 Started by user Ian Young
Running as SYSTEM
Building on master in workspace <http://127.0.0.1:1583/jenkins/job/java-idp-tomcat-base-9.0/ws/>
No credentials specified
 > git rev-parse --is-inside-work-tree # timeout=10
Fetching changes from the remote Git repository
 > git config remote.origin.url git://git.shibboleth.net/java-idp-tomcat-base # timeout=10
Fetching upstream changes from git://git.shibboleth.net/java-idp-tomcat-base
 > git --version # timeout=10
 > git fetch --tags --progress git://git.shibboleth.net/java-idp-tomcat-base +refs/heads/*:refs/remotes/origin/*
 > git rev-parse refs/remotes/origin/9.0^{commit} # timeout=10
 > git rev-parse refs/remotes/origin/refs/heads/9.0^{commit} # timeout=10
Checking out Revision cb30877ef1ddd037c08559d45e9dc930641f63b7 (refs/remotes/origin/9.0)
 > git config core.sparsecheckout # timeout=10
 > git checkout -f cb30877ef1ddd037c08559d45e9dc930641f63b7
Commit message: "Update from Tomcat 9.0.12 distribution"
 > git rev-list --no-walk cb30877ef1ddd037c08559d45e9dc930641f63b7 # timeout=10
Parsing POMs
Established TCP socket on 44112
[workspace] $ /opt/jdk/jdk-7/bin/java -cp /var/lib/jenkins/plugins/maven-plugin/WEB-INF/lib/maven35-agent-1.13.jar:/opt/maven_home/boot/plexus-classworlds-2.5.2.jar:/opt/maven_home/conf/logging jenkins.maven3.agent.Maven35Main /opt/maven_home /var/cache/jenkins/war/WEB-INF/lib/remoting-3.29.jar /var/lib/jenkins/plugins/maven-plugin/WEB-INF/lib/maven35-interceptor-1.13.jar /var/lib/jenkins/plugins/maven-plugin/WEB-INF/lib/maven3-interceptor-commons-1.13.jar 44112
Exception in thread "main" java.lang.UnsupportedClassVersionError: jenkins/maven3/agent/Maven35Main : Unsupported major.minor version 52.0
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
	at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
	at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
ERROR: Failed to launch Maven. Exit code = 1