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