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https://issues.apache.org/jira/browse/COLLECTIONS-872?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17903914#comment-17903914
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Gary D. Gregory commented on COLLECTIONS-872:
---------------------------------------------
[~chrimle]
You're in the right place.
> MultiKeyMap: Key-objects are stored as reference, making it possible to
> modify the Map externally
> -------------------------------------------------------------------------------------------------
>
> Key: COLLECTIONS-872
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-872
> Project: Commons Collections
> Issue Type: Bug
> Components: Map
> Affects Versions: 2.0, 2.1, 2.1.1, 3.0, 3.1, 3.2, 3.2.1, 3.2.2,
> 4.0-alpha1, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5.0-M1, 4.5.0-M2
> Reporter: Christopher Molin
> Priority: Critical
>
> When using MultiKeyMap, the keys are stored as-is (as references).
> This leads to the following problem:
> # Create a MultiKeyMap, with key(s) of a type (class/{-}record{-}) which has
> some fields.
> # Use multiKeyMap.put(T... keys, V value), to create an entry in the Map, to
> map the keys to a value
> # Use multiKeyMap.get(T... keys), to verify that the mapping exists and
> returns the expected value.
> # Modify/alter any of the objects used as a key. It is enough to change the
> value of any member field of any of the objects.
> # Use multiKeyMap.get(T... keys) again, however, now there is no mapping for
> these keys!
> # Use multiKeyMap.get(T... keys) with the new modified/altered objects, and
> it will return the expected value
> This is potentially a major issue - especially for those unaware of this
> behavior!
>
> This is a problem since the introduction in v1.17
>
> Potential Solution:
> Calculate the Hash of the keys, and use those as keys. This way, would not be
> subject to external modification.
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