Summary

The classes javax.management.AttributeList, and javax.management.relation.RoleList and UnresolvedRoleList, have a historical feature where they accept objects of the wrong type, and only check for wrong objects when (and after) the "asList()" method is called. This feature should be removed, and these classes should never accept the wrong kind of Object.

Problem

These three classes have unnecessary complexity around type-checking Objects which are added. There is no need for these classes to hold Objects of the wrong type.

This feature was added between JDK1.5 and JDK1.6, for compatibility. The compatibility issue was only ever minor: prior JMX releases 1.2 and 1.3 and the release in JDK 1.5 had methods which accepted the specific class. Therefore even in JDK1.6, there was no expectation that these classes could hold anything other than the specific type.

Adding alien Objects has been specifically strongly discouraged in the AttributeList API docs, and should now be illegal, and the unnecessary complexity removed.

Solution

Simply enforce the checking of types in these classes. Fail fast, in the obscure case that incorrect types are used.

Specification

API changes: API doc text updates. No disruptive or incompatible API changes.

• In the class AttributeList:

Remove the text: "For compatibility reasons, it is possible, though highly discouraged, to add objects to an AttributeList that are not instances of Attribute." and up to: "An AttributeList becomes type-safe when the method asList() is called on it."

Replace with: "It is not permitted to add objects to an AttributeList that are not instances of Attribute. This will produce an IllegalArgumentException."

In the "asList()" method, remove: "If this method has ever been called on a given AttributeList instance, a subsequent attempt to add an object to that instance which is not an Attribute will fail with an IllegalArgumentException. For compatibility reasons, an AttributeList on which this method has never been called does allow objects other than Attributes to be added."

Change wording of some throws messages for IllegalArgumentException.

• In the class RoleList:

Remove the same wording from the "asList()" method. Change wording of some throws messages for IllegalArgumentException. Add inheric doc tags for clarity.

• In the class RoleUnresolvedList:

Remove the same wording from the "asList()" method. Change wording of some throws messages for IllegalArgumentException. Add inheric doc tags for clarity.

In the attached specdiff_8359809.zip file, see:

specdiff/AttributeList.html specdiff/relation/RoleList.html specdiff/relation/RoleUnresolvedList.html

Github reference: https://github.com/openjdk/jdk/pull/25856