ManagementFactory.getGarbageCollectorMXBeans() returns an empty list when Java started with -XX:+UseConcMarkSweepGC. JDK is 7 b110.
Here is a snippet from a Solaris SPARC Client VM -Xmixed failure
of LastGCInfo.java:

----------System.err:(13/706)----------
java.lang.RuntimeException: No GcInfo returned
at LastGCInfo.main(LastGCInfo.java:59)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:613)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:94)
at java.lang.Thread.run(Thread.java:729)

JavaTest Message: Test threw exception: java.lang.RuntimeException: No GcInfo returned
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: No GcInfo returned
result: Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: No GcInfo returned


test result: Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: No GcInfo returned


Here is the URL for the failing config:

http://vmsqe.russia/execution/results/JDK7/PROMOTION/VM/7/b110/ConcMarkSweepGC/javase/solaris-sparc/client/mixed/solaris-sparc_javase_client_mixed_JT_JDK_com_sun_management/analysis.html
Here is a snippet from a Solaris SPARC Client VM -Xmixed failure
of GcInfoCompositeType.java:

----------System.out:(8/395)----------
Testing java.lang:type=GarbageCollector,name=ParNew
Items at start: [startTime, id, duration, memoryUsageBeforeGc, memoryUsageAfterGc, endTime]
No type-specific items
Value of attribute null
Testing java.lang:type=GarbageCollector,name=ConcurrentMarkSweep
Items at start: [startTime, id, duration, memoryUsageBeforeGc, memoryUsageAfterGc, endTime]
No type-specific items
Value of attribute null
----------System.err:(13/715)----------
java.lang.Exception: No MXBeans were tested
at GcInfoCompositeType.main(GcInfoCompositeType.java:54)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:613)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:94)
at java.lang.Thread.run(Thread.java:729)

JavaTest Message: Test threw exception: java.lang.Exception: No MXBeans were tested
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.Exception: No MXBeans were tested
result: Failed. Execution failed: `main' threw exception: java.lang.Exception: No MXBeans were tested


test result: Failed. Execution failed: `main' threw exception: java.lang.Exception: No MXBeans were tested


Here is the URL for the failing config:

http://vmsqe.russia/execution/results/JDK7/PROMOTION/VM/7/b110/ConcMarkSweepGC/javase/solaris-sparc/client/mixed/solaris-sparc_javase_client_mixed_JT_JDK_java_lang/analysis.html