Going from 1.499 to 1.500 results in the following exception when trying to build projects with JDK5. Switching back to 1.499 solves the issue.

The job is running with this configuration:
Executing Maven: -B -f /var/opt/data/jenkins/workspace/pro031/pom.xml --fail-at-end -V -e help:effective-settings help:active-profiles clean package
Apache Maven 3.0.4 (r1232337; 2012-01-17 09:44:56+0100)
Maven home: /opt/maven/bin-3.0.4
Java version: 1.5.0, vendor: IBM Corporation
Java home: /opt/java/java-ibmsdk-x86_64_5.0_SR15/jre
Default locale: en_US, platform encoding: ANSI_X3.4-1968
OS name: "linux", version: "2.6.32-279.el6.x86_64", arch: "amd64", family: "unix"

...

[INFO] ------------------------------------------------------------------------
[INFO] Building pro031 1.0.4-SNAPSHOT
[INFO] ------------------------------------------------------------------------
mojoStarted org.apache.maven.plugins:maven-help-plugin:2.1.1(default-cli)
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchStandard(Launcher.java:329)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:239)
at org.jvnet.hudson.maven3.agent.Maven3Main.launch(Maven3Main.java:158)
at hudson.maven.Maven3Builder.call(Maven3Builder.java:100)
at hudson.maven.Maven3Builder.call(Maven3Builder.java:66)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
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:284)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:678)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:703)
at java.lang.Thread.run(Thread.java:813)
Caused by: java.lang.ClassFormatError: Failed to load org.apache.commons.codec.binary.Base64OutputStream
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:193)
at hudson.remoting.RemoteClassLoader.findClass(RemoteClassLoader.java:144)
at java.lang.ClassLoader.loadClass(ClassLoader.java:650)
at java.lang.ClassLoader.loadClass(ClassLoader.java:616)
at java.lang.J9VMInternals.verifyImpl(Native Method)
at java.lang.J9VMInternals.verify(J9VMInternals.java:69)
at java.lang.J9VMInternals.verify(J9VMInternals.java:67)
at java.lang.J9VMInternals.initialize(J9VMInternals.java:131)
at hudson.maven.util.ExecutionEventLogger.mojoStarted(ExecutionEventLogger.java:274)
at hudson.maven.Maven3Builder$MavenExecutionListener.mojoStarted(Maven3Builder.java:396)
at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire(DefaultExecutionEventCatapult.java:84)
at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire(DefaultExecutionEventCatapult.java:42)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:203)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.jvnet.hudson.maven3.launcher.Maven3Launcher.main(Maven3Launcher.java:79)
... 18 more
Caused by: java.lang.UnsupportedClassVersionError: (org/apache/commons/codec/binary/Base64OutputStream) bad major version at offset=6
at java.lang.ClassLoader.defineClassImpl(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:267)
at java.lang.ClassLoader.defineClass(ClassLoader.java:204)
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:191)
... 39 more
channel stopped
ERROR: Failed to parse POMs
hudson.util.IOException2: java.lang.reflect.InvocationTargetException
at hudson.maven.Maven3Builder.call(Maven3Builder.java:162)
at hudson.maven.Maven3Builder.call(Maven3Builder.java:66)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
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:284)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:678)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:703)
at java.lang.Thread.run(Thread.java:813)
Caused by: java.lang.Exception: java.lang.reflect.InvocationTargetException
at org.jvnet.hudson.maven3.agent.Maven3Main.launch(Maven3Main.java:161)
at hudson.maven.Maven3Builder.call(Maven3Builder.java:100)
... 10 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchStandard(Launcher.java:329)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:239)
at org.jvnet.hudson.maven3.agent.Maven3Main.launch(Maven3Main.java:158)
... 11 more
Caused by: java.lang.ClassFormatError: Failed to load org.apache.commons.codec.binary.Base64OutputStream
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:193)
at hudson.remoting.RemoteClassLoader.findClass(RemoteClassLoader.java:144)
at java.lang.ClassLoader.loadClass(ClassLoader.java:650)
at java.lang.ClassLoader.loadClass(ClassLoader.java:616)
at java.lang.J9VMInternals.verifyImpl(Native Method)
at java.lang.J9VMInternals.verify(J9VMInternals.java:69)
at java.lang.J9VMInternals.verify(J9VMInternals.java:67)
at java.lang.J9VMInternals.initialize(J9VMInternals.java:131)
at hudson.maven.util.ExecutionEventLogger.mojoStarted(ExecutionEventLogger.java:274)
at hudson.maven.Maven3Builder$MavenExecutionListener.mojoStarted(Maven3Builder.java:396)
at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire(DefaultExecutionEventCatapult.java:84)
at org.apache.maven.lifecycle.internal.DefaultExecutionEventCatapult.fire(DefaultExecutionEventCatapult.java:42)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:203)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.jvnet.hudson.maven3.launcher.Maven3Launcher.main(Maven3Launcher.java:79)
... 18 more
Caused by: java.lang.UnsupportedClassVersionError: (org/apache/commons/codec/binary/Base64OutputStream) bad major version at offset=6
at java.lang.ClassLoader.defineClassImpl(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:267)
at java.lang.ClassLoader.defineClass(ClassLoader.java:204)
at hudson.remoting.RemoteClassLoader.loadClassFile(RemoteClassLoader.java:191)
... 39 more