Projects build with jdk1.5.0_12 fail since the upgrade to Jenkins 1.520

<===[JENKINS REMOTING CAPACITY]===>channel started
erreicht: 902
ERROR: Failed to parse POMs
java.io.IOException: Remote call on Channel to Maven [D:\apps\Java\jdk1.5.0_12/bin/java, -cp, D:\apps\Jenkins\plugins\maven-plugin\WEB-INF\lib\maven-agent-1.3.jar;D:\apps\Maven\apache-maven-2.2.1\boot\classworlds-1.1.jar, hudson.maven.agent.Main, D:\apps\Maven\apache-maven-2.2.1, D:\apps\Jenkins\war\WEB-INF\lib\remoting-2.24.jar, D:\apps\Jenkins\plugins\maven-plugin\WEB-INF\lib\maven-interceptor-1.3.jar, 51928, D:\apps\Jenkins\plugins\maven-plugin\WEB-INF\lib\maven2.1-interceptor-1.2.jar] failed
at hudson.remoting.Channel.call(Channel.java:731)
at hudson.maven.ProcessCache$MavenProcess.<init>(ProcessCache.java:112)
at hudson.maven.ProcessCache.get(ProcessCache.java:231)
at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.doRun(MavenModuleSetBuild.java:694)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:586)
at hudson.model.Run.execute(Run.java:1593)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:491)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:247)
Caused by: java.lang.ClassFormatError: Failed to load hudson.maven.ProcessCache$GetSystemProperties
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:291)
at hudson.remoting.RemoteClassLoader.findClass(RemoteClassLoader.java:229)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:242)
at hudson.remoting.MultiClassLoaderSerializer$Input.resolveClass(MultiClassLoaderSerializer.java:113)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1544)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1466)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1699)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1305)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:348)
at hudson.remoting.UserRequest.deserialize(UserRequest.java:182)
at hudson.remoting.UserRequest.perform(UserRequest.java:98)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:326)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)
at java.util.concurrent.FutureTask.run(FutureTask.java:123)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.UnsupportedClassVersionError: Bad version number in .class file
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.lang.ClassLoader.defineClass(ClassLoader.java:465)
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:289)
... 22 more