Unsupported Class Version Error when running testsuite with JDK6

Description of problem:

Unsupported Class Version Error is thrown when running testsuite with JDK6.

The main error messages:

[ERROR] java.lang.UnsupportedClassVersionError: org/infinispan/protostream/sampledomain/User : Unsupported major.minor version 51.0

[ERROR] java.lang.UnsupportedClassVersionError: org/ops4j/pax/exam/Option : Unsupported major.minor version 51.0

Extracted logs:

[INFO] Reactor Summary:
[INFO]
[INFO] Infinispan BOM .................................... SUCCESS [10.406s]
[INFO] Infinispan Common Parent .......................... SUCCESS [17.060s]
[INFO] Infinispan Commons ................................ SUCCESS [26.115s]
[INFO] Infinispan Core ................................... SUCCESS [1:03:33.709s]
[INFO] Parent pom for server modules ..................... SUCCESS [3.556s]
[INFO] Infinispan Server - Core Components ............... SUCCESS [1:07.008s]
[INFO] Infinispan Query DSL API .......................... SUCCESS [3.722s]
[INFO] Infinispan Object Filtering API ................... SUCCESS [8.841s]
[INFO] Parent pom for cachestore modules ................. SUCCESS [1.038s]
[INFO] Infinispan JDBC CacheStore ........................ SUCCESS [10:10.126s]
[INFO] Parent pom for the Lucene integration modules ..... SUCCESS [1.188s]
[INFO] Infinispan integration with Lucene v.3.x .......... SUCCESS [37.289s]
[INFO] Infinispan Lucene Directory Implementation ........ SUCCESS [3.409s]
[INFO] Infinispan Query API .............................. SUCCESS [5:25.030s]
[INFO] Infinispan Tools .................................. SUCCESS [8.149s]
[INFO] Infinispan Remote Query Client .................... SUCCESS [2.575s]
[INFO] Infinispan Remote Query Server .................... FAILURE [1:09.702s]
[INFO] Infinispan JPA CacheStore ......................... SUCCESS [4:35.809s]
[INFO] Infinispan Hot Rod Server ......................... FAILURE [3:21.935s]
[INFO] Infinispan Hot Rod Client ......................... FAILURE [11.828s]
[INFO] Parent pom for compatibility modules .............. SUCCESS [0.697s]
[INFO] infinispan-custom52x-store ........................ SUCCESS [25.898s]
[INFO] infinispan-adaptor52x ............................. SUCCESS [3:59.482s]
[INFO] Infinispan remote CacheStore ...................... SUCCESS [44.130s]
[INFO] Infinispan LevelDB CacheStore ..................... SUCCESS [6:05.134s]
[INFO] Infinispan REST Server ............................ SUCCESS [1:31.259s]
[INFO] Infinispan REST CacheStore ........................ SUCCESS [15.390s]
[INFO] Infinispan Memcached Server ....................... SUCCESS [1:34.134s]
[INFO] Parent pom for uberjar modules .................... SUCCESS [0.037s]
[INFO] Infinispan Embedded ............................... SUCCESS [31.958s]
[INFO] Infinispan Embedded Query ......................... SUCCESS [40.679s]
[INFO] Infinispan Remote Client .......................... FAILURE [4.012s]
[INFO] Infinispan RHQ Plugin ............................. SUCCESS [37.664s]
[INFO] Infinispan CLI Server ............................. SUCCESS [41.473s]
[INFO] Infinispan CLI Client ............................. SUCCESS [11.122s]
[INFO] Infinispan CDI support ............................ SUCCESS [1:34.483s]
[INFO] Infinispan AS/EAP modules for library ............. SUCCESS [23.125s]
[INFO] Infinispan AS/EAP modules for remote client ....... SUCCESS [1.783s]
[INFO] Integration tests: Security Tests ................. SUCCESS [7:57.420s]
[INFO] Integration tests: SecurityManager tests .......... SUCCESS [15.094s]
[INFO] Integration tests: Karaf .......................... FAILURE [52.078s]
[INFO] Integration tests: AS Module Integration Tests .... SUCCESS [1:35.135s]
[INFO] Integration tests: AS Remote Client Module Integration Tests SUCCESS [52.983s]
[INFO] Integration tests: Lucene Directory with Infinispan Query SUCCESS [13.914s]
[INFO] Integration tests: Infinispan compatibility mode .. SUCCESS [25.802s]
[INFO] Infinispan Embedded Integration Tests ............. SUCCESS [5.941s]
[INFO] Infinispan Embedded Query Integration Tests ....... SUCCESS [4.319s]
[INFO] Infinispan Remote Client Integration Tests ........ FAILURE [0.080s]
[INFO] Infinispan Distribution ........................... SUCCESS [0.708s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2:03:47.228s
[INFO] Finished at: Fri Oct 24 07:33:04 EDT 2014
[INFO] Final Memory: 145M/446M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test (default-test) on project infinispan-remote-query-server: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test failed: The forked VM terminated without saying properly goodbye. VM crash or System.exit called ?
[ERROR] Command was/bin/sh -c cd /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/remote-query/remote-query-server && /qa/tools/opt/amd64/jdk1.6.0_last/bin/java -Xmx1536m -XX:MaxPermSize=384m -Dsun.nio.ch.bugLevel -jar /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/remote-query/remote-query-server/target/surefire/surefirebooter1225172043033571111.jar /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/remote-query/remote-query-server/target/surefire/surefire4460884784028612739tmp /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/remote-query/remote-query-server/target/surefire/surefire_61815997041197751408tmp
[ERROR] -> [Help 1]
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test (default-test) on project infinispan-server-hotrod: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test failed: The forked VM terminated without saying properly goodbye. VM crash or System.exit called ?
[ERROR] Command was/bin/sh -c cd /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/server/hotrod && /qa/tools/opt/amd64/jdk1.6.0_last/bin/java -Xmx1536m -XX:MaxPermSize=384m -Dsun.nio.ch.bugLevel -jar /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/server/hotrod/target/surefire/surefirebooter8896904403305648242.jar /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/server/hotrod/target/surefire/surefire878622548590911280tmp /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/server/hotrod/target/surefire/surefire_86027626310850569139tmp
[ERROR] -> [Help 1]
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test (default-test) on project infinispan-client-hotrod: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test failed: There was an error in the forked process
[ERROR] java.lang.UnsupportedClassVersionError: org/infinispan/protostream/sampledomain/User : Unsupported major.minor version 51.0
[ERROR] at java.lang.ClassLoader.defineClass1(Native Method)
[ERROR] at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
[ERROR] at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
[ERROR] at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
[ERROR] at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
[ERROR] at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
[ERROR] at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
[ERROR] at java.security.AccessController.doPrivileged(Native Method)
[ERROR] at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
[ERROR] at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
[ERROR] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
[ERROR] at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
[ERROR] at java.lang.Class.getDeclaredMethods0(Native Method)
[ERROR] at java.lang.Class.privateGetDeclaredMethods(Class.java:2436)
[ERROR] at java.lang.Class.getDeclaredMethods(Class.java:1793)
[ERROR] at org.testng.internal.annotations.AnnotationHelper.findMethodsWithAnnotation(AnnotationHelper.java:214)
[ERROR] at org.testng.internal.TestNGMethodFinder.getTestMethods(TestNGMethodFinder.java:49)
[ERROR] at org.testng.TestClass.initMethods(TestClass.java:123)
[ERROR] at org.testng.TestClass.init(TestClass.java:86)
[ERROR] at org.testng.TestClass.<init>(TestClass.java:45)
[ERROR] at org.testng.TestRunner.initMethods(TestRunner.java:427)
[ERROR] at org.testng.TestRunner.init(TestRunner.java:235)
[ERROR] at org.testng.TestRunner.init(TestRunner.java:205)
[ERROR] at org.testng.TestRunner.<init>(TestRunner.java:153)
[ERROR] at org.testng.SuiteRunner$DefaultTestRunnerFactory.newTestRunner(SuiteRunner.java:522)
[ERROR] at org.testng.SuiteRunner.init(SuiteRunner.java:157)
[ERROR] at org.testng.SuiteRunner.<init>(SuiteRunner.java:111)
[ERROR] at org.testng.TestNG.createSuiteRunner(TestNG.java:1273)
[ERROR] at org.testng.TestNG.createSuiteRunners(TestNG.java:1260)
[ERROR] at org.testng.TestNG.runSuitesLocally(TestNG.java:1114)
[ERROR] at org.testng.TestNG.run(TestNG.java:1031)
[ERROR] at org.apache.maven.surefire.testng.TestNGExecutor.run(TestNGExecutor.java:77)
[ERROR] at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.executeMulti(TestNGDirectoryTestSuite.java:189)
[ERROR] at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.execute(TestNGDirectoryTestSuite.java:105)
[ERROR] at org.apache.maven.surefire.testng.TestNGProvider.invoke(TestNGProvider.java:117)
[ERROR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray2(ReflectionUtils.java:208)
[ERROR] at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:159)
[ERROR] at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:87)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:95)
[ERROR] -> [Help 1]
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:2.3:shade (default) on project infinispan-remote: Error creating shaded jar: /mnt/hudson_workspace/workspace/edg-60-ispn-testsuite-rhel/6a814865/infinispan/client/hotrod-client/target/classes (Is a directory) -> [Help 2]
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test (default-test) on project integrationtests-osgi: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.14.1:test failed: There was an error in the forked process
[ERROR] java.lang.UnsupportedClassVersionError: org/ops4j/pax/exam/Option : Unsupported major.minor version 51.0
[ERROR] at java.lang.ClassLoader.defineClass1(Native Method)
[ERROR] at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
[ERROR] at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
[ERROR] at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
[ERROR] at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
[ERROR] at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
[ERROR] at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
[ERROR] at java.security.AccessController.doPrivileged(Native Method)
[ERROR] at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
[ERROR] at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
[ERROR] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
[ERROR] at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
[ERROR] at java.lang.Class.getDeclaredMethods0(Native Method)
[ERROR] at java.lang.Class.privateGetDeclaredMethods(Class.java:2436)
[ERROR] at java.lang.Class.getMethod0(Class.java:2679)
[ERROR] at java.lang.Class.getMethod(Class.java:1605)
[ERROR] at org.apache.maven.surefire.util.ReflectionUtils.tryGetMethod(ReflectionUtils.java:57)
[ERROR] at org.apache.maven.surefire.common.junit3.JUnit3TestChecker.isSuiteOnly(JUnit3TestChecker.java:64)
[ERROR] at org.apache.maven.surefire.common.junit3.JUnit3TestChecker.isValidJUnit3Test(JUnit3TestChecker.java:59)
[ERROR] at org.apache.maven.surefire.common.junit3.JUnit3TestChecker.accept(JUnit3TestChecker.java:54)
[ERROR] at org.apache.maven.surefire.common.junit4.JUnit4TestChecker.accept(JUnit4TestChecker.java:51)
[ERROR] at org.apache.maven.surefire.util.DefaultScanResult.applyFilter(DefaultScanResult.java:97)
[ERROR] at org.apache.maven.surefire.junitcore.JUnitCoreProvider.scanClassPath(JUnitCoreProvider.java:179)
[ERROR] at org.apache.maven.surefire.junitcore.JUnitCoreProvider.invoke(JUnitCoreProvider.java:132)
[ERROR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray2(ReflectionUtils.java:208)
[ERROR] at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:159)
[ERROR] at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:87)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
[ERROR] at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:95)
[ERROR] -> [Help 1]