MBean*Info.hashCode : NPE

I have a test testing the method hashCode of the following classes:
   MBeanAttributeInfo
   MBeanConstructorInfo
   MBeanOperationInfo
   MBeanParameterInfo
   MBeanInfo

here is the result:
---Testing on MBeanAttributeInfo...
OK: MBeanAttributeInfo.equals worked with a null class name
--->KO!!! MBeanAttributeInfo.hashCode got NPE with a null class name
OK: MBeanAttributeInfo.toString worked with a null class name
OK: MBeanAttributeInfo.equals worked with a null type
--->KO!!! MBeanAttributeInfo.hashCode got NPE with a null type
OK: MBeanAttributeInfo.toString worked with a null type
OK: MBeanAttributeInfo.equals worked with a null description
OK: MBeanAttributeInfo.hashCode worked with a null description
OK: MBeanAttributeInfo.toString worked with a null description

---Testing on MBeanConstructorInfo...
OK: MBeanConstructorInfo.equals worked with a null name
--->KO!!! MBeanConstructorInfo.hashCode got NPE with a null name
OK: MBeanConstructorInfo.toString worked with a null name
OK: MBeanConstructorInfo.equals worked with a null description
OK: MBeanConstructorInfo.hashCode worked with a null description
OK: MBeanConstructorInfo.toString worked with a null description
OK: MBeanConstructorInfo.equals worked with a null MBeanParameterInfo
OK: MBeanConstructorInfo.hashCode worked with a null MBeanParameterInfo
OK: MBeanConstructorInfo.toString worked with a null MBeanParameterInfo
OK: MBeanConstructorInfo.equals worked with a null descriptor
OK: MBeanConstructorInfo.hashCode worked with a null descriptor
OK: MBeanConstructorInfo.toString worked with a null descriptor

---Testing on MBeanOperationInfo...
OK: MBeanOperationInfo.equals worked with a null name
--->KO!!! MBeanOperationInfo.hashCode got NPE with a null name
OK: MBeanOperationInfo.toString worked with a null name
OK: MBeanOperationInfo.equals worked with a null description
OK: MBeanOperationInfo.hashCode worked with a null description
OK: MBeanOperationInfo.toString worked with a null description
OK: MBeanOperationInfo.equals worked with a null MBeanParameterInfo
OK: MBeanOperationInfo.hashCode worked with a null MBeanParameterInfo
OK: MBeanOperationInfo.toString worked with a null MBeanParameterInfo
OK: MBeanOperationInfo.equals worked with a null type
--->KO!!! MBeanOperationInfo.hashCode got NPE with a null type
OK: MBeanOperationInfo.toString worked with a null type
OK: MBeanOperationInfo.equals worked with a null native impact
--->KO!!! MBeanOperationInfo.hashCode got NPE with a null native impact
OK: MBeanOperationInfo.toString worked with a null native impact
OK: MBeanOperationInfo.equals worked with a null Descriptor
--->KO!!! MBeanOperationInfo.hashCode got NPE with a null Descriptor
OK: MBeanOperationInfo.toString worked with a null Descriptor

---Testing on MBeanParameterInfo...
OK: MBeanParameterInfo.equals worked with a null name
--->KO!!! MBeanParameterInfo.hashCode got NPE with a null name
OK: MBeanParameterInfo.toString worked with a null name
OK: MBeanParameterInfo.equals worked with a null description
--->KO!!! MBeanParameterInfo.hashCode got NPE with a null description
OK: MBeanParameterInfo.toString worked with a null description
OK: MBeanParameterInfo.equals worked with a null description
OK: MBeanParameterInfo.hashCode worked with a null description
OK: MBeanParameterInfo.toString worked with a null description
OK: MBeanParameterInfo.equals worked with a null Descriptor
OK: MBeanParameterInfo.hashCode worked with a null Descriptor
OK: MBeanParameterInfo.toString worked with a null Descriptor

---Testing on MBeanInfo...
OK: MBeanInfo.equals worked with a null class name
--->KO!!! MBeanInfo.hashCode got NPE with a null class name
OK: MBeanInfo.toString worked with a null class name
OK: MBeanInfo.equals worked with a null name
OK: MBeanInfo.hashCode worked with a null name
OK: MBeanInfo.toString worked with a null name
OK: MBeanInfo.equals worked with a null description
OK: MBeanInfo.hashCode worked with a null description
OK: MBeanInfo.toString worked with a null description
OK: MBeanInfo.equals worked with a null attrInfos
OK: MBeanInfo.hashCode worked with a null attrInfos
OK: MBeanInfo.toString worked with a null attrInfos
OK: MBeanInfo.equals worked with a null operaInfos
OK: MBeanInfo.hashCode worked with a null operaInfos
OK: MBeanInfo.toString worked with a null operaInfos
OK: MBeanInfo.equals worked with a null notifInfos
OK: MBeanInfo.hashCode worked with a null notifInfos
OK: MBeanInfo.toString worked with a null notifInfos
Exception in thread "main" java.lang.RuntimeException: Test failed: 10
at MBeanInfoEqualsTest.main(MBeanInfoEqualsTest.java:160)
Java Result: 1