[jira] [Commented] (SLING-9774) The ValueMapUtil#merge behavior is different from the deprecated CompositeValueMap

["Julian Sedding (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SLING-9774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17203108#comment-17203108 ] 

Julian Sedding commented on SLING-9774:
---------------------------------------

[~enorman] A simpler fix that passes your test would be the following:

{code:java}
    @Override
    public Object get(final Object key) {
        return valueMaps.stream()
                .filter(vm -> vm.containsKey(key)) // SLING-9774
                .findFirst()
                .map(vm -> vm.get(key))
                .orElse(null);
    }
{code}

> The ValueMapUtil#merge behavior is different from the deprecated CompositeValueMap
> ----------------------------------------------------------------------------------
>
>                 Key: SLING-9774
>                 URL: https://issues.apache.org/jira/browse/SLING-9774
>             Project: Sling
>          Issue Type: Bug
>    Affects Versions: API 2.23.0
>            Reporter: Eric Norman
>            Assignee: Eric Norman
>            Priority: Major
>             Fix For: API 2.23.2
>
>
> CompositeValueMap has been marked as deprecated and the recommendation was to replace those usages with ValueMapUtil#merge(ValueMap...)}
> Unfortunately it looks like implementation from ValueMapUtil#merge has different behavior when it comes to handling of entries in the map where the key is supplied but the value is null.
> My use case is that in a few places I have used the key=null behavior of CompositeValueMap to hide entries in a wrapped ValueMap and those uses cases don't work the same after switching to ValueMapUtil#merge(ValueMap...)}.
> To be compatible with the deprecated CompositeValueMap, the MergingValueMap#get impl should not automatically filter entries whose value is null.  Instead it should only filter when the value is null and the map does not contain the key.   A null value doesn't always mean that the map didn't have an entry for the key.



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