Established TCP socket on 38891
Exception in thread "main" java.lang.UnsupportedClassVersionError: hudson/remoting/Launcher : 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 org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:386)
	at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
	at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
	at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:230)
	at org.jvnet.hudson.maven3.agent.Maven3Main.main(Maven3Main.java:138)
	at org.jvnet.hudson.maven3.agent.Maven3Main.main(Maven3Main.java:70)
Established TCP socket on 44511
<===[JENKINS REMOTING CAPACITY]===>   channel started
Executing Maven:  -B -f /var/lib/jenkins/jobs/DenizenCore/workspace/pom.xml clean install javadoc:javadoc
[INFO] Scanning for projects...
[HUDSON] Collecting dependencies info
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building DenizenCore 1.20
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:2.4.1:clean (default-clean) @ denizencore ---
[INFO] Deleting /var/lib/jenkins/jobs/DenizenCore/workspace/target
[INFO] 
[INFO] --- maven-resources-plugin:2.4.3:resources (default-resources) @ denizencore ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] 
[INFO] --- maven-compiler-plugin:2.3.2:compile (default-compile) @ denizencore ---
[INFO] Compiling 106 source files to /var/lib/jenkins/jobs/DenizenCore/workspace/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] Failure executing javac,  but could not parse the error:
javac: invalid target release: 1.8
Usage: javac <options> <source files>
use -help for a list of possible options

[INFO] 1 error
[INFO] -------------------------------------------------------------
[WARNING] Attempt to (de-)serialize anonymous class hudson.maven.reporters.MavenArtifactArchiver$2; see: https://jenkins.io/redirect/serialization-of-anonymous-classes/
[WARNING] Attempt to (de-)serialize anonymous class org.jfrog.hudson.maven2.MavenDependenciesRecorder$1; see: https://jenkins.io/redirect/serialization-of-anonymous-classes/
[WARNING] Attempt to (de-)serialize anonymous class hudson.maven.reporters.MavenFingerprinter$1; see: https://jenkins.io/redirect/serialization-of-anonymous-classes/
Started calculate disk usage of build
Finished Calculation of disk usage of build in 0 seconds
Started calculate disk usage of workspace
Finished Calculation of disk usage of workspace in 0 seconds
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3.102s
[INFO] Finished at: Fri Oct 12 17:03:54 GMT 2018
[INFO] Final Memory: 12M/118M
[INFO] ------------------------------------------------------------------------
Waiting for Jenkins to finish collecting data
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.3.2:compile (default-compile) on project denizencore: Compilation failure
[ERROR] Failure executing javac,  but could not parse the error:
[ERROR] javac: invalid target release: 1.8
[ERROR] Usage: javac <options> <source files>
[ERROR] use -help for a list of possible options
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException