In jconsole the operations for the ThreadMXBean shows extra symbols
like 'class [J' and ';' in return parameters.

This can be reproduced in all platforms.

How to reproduce this:
1) Start jconsole
2) Attach to any java process (even to jconsole)
3) Go to the MBeans tab
4) In the MBeans tree select the java.lang.Threading MBean
5) Go to the Operations tab for the Threading MBean
you should see the above said special chars.

Please see the attached png file for more information (ThreadingMBean.png).
This is not a bug in jconsole but in the MXBean framework.

When a given MXBean's operation cannot be defined by an OpenMBeanOperationInfo
because at least one of its parameters cannot use OpenMBeanParameterInfo the
ReturnType should be either the OpenReturnType.getClassName() if the return
type can be mapped to an OpenType without breaking backwards compatibility
or the original type corresponding to the originalType field in the descriptor
for the MBeanOperationInfo if OpenType cannot be used.