In order to avoid nested tabs inside the MBeans tab, and to improve navigability
and accessibility the attributes/operations/notifications tabs should be folded
into the main MBean tree, and the Info tab and Descriptor data displayed with
each node (contextually).

MBeans tab´s MBean tree structure and sheet view should look like:

Domain node ---> empty
  Intermediate key/value pair node ---> empty
    Last key/value pair denoting an MBean node ---> Old Info inner tabbed pane plus MBeanInfo (including Descriptor)
      Attributes node ---> Old Attributes inner tabbed pane
        Attribute name node ---> MBeanAttributeInfo (including Descriptor)
      Operations node ---> Old Operations inner tabbed pane
        Operation name node ---> MBeanOperationInfo (including Descriptor)
          Parameter name node ---> MBeanParameterInfo (including Descriptor)
      Notifications node ---> Old Notifications inner tabbed pane
        Notification node ---> MBeanNotificationInfo (including Descriptor)
      Constructors node ---> empty
        Constructor name node ---> MBeanConstructorInfo (including Descriptor)
          Parameter name node ---> MBeanParameterInfo (including Descriptor)

For example,

Tree Display
---- -------

+ java.lang Empty for now (could show overview of children)
| |
| + Memory Show content from the old Info tab, plus MBeanInfo and Descriptor
| | |
| | + Attributes Show content from the old Attributes tab
| | | |
| | | + HeapMemoryUsage Show this attribute´s MBeanAttributeInfo and Descriptor
| | | |
| | | + NonHeapMemoryUsage Idem
| | | |
| | | + ... Idem
| | | |
| | + Operations Show content of the old Operations tab
| | | |
| | | + gc Show this operation´s MBeanOperationInfo and Descriptor,
| | | | plus the parameters' info and descriptors in a table
| | | |
| | | + ... Idem
| | | |
| | + Notifications Show content of the old Notifications tab
| | | |
| | | + javax.management.Notif... Show this notification´s MBeanNotificationInfo and Descriptor
| | | |
| | | + ... Idem