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https://issues.apache.org/jira/browse/GROOVY-10859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17642647#comment-17642647
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Eric Milles commented on GROOVY-10859:
--------------------------------------
Appears to work fine under static compilation in case you need a quick
workaround.
> Regression in invoking method references to methods from List class when
> called on empty lists
> ----------------------------------------------------------------------------------------------
>
> Key: GROOVY-10859
> URL: https://issues.apache.org/jira/browse/GROOVY-10859
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 4.0.0
> Reporter: Marcin Erdmann
> Assignee: Eric Milles
> Priority: Major
>
> While migrating from Groovy 3 to Groovy 4 I have uncovered a regression in
> how method references to methods on {{List}} are invoked when called on empty
> lists. The following test case passes on Groovy 3:
> {code:java}
> def "method references from List class are invoked correctly on empty
> lists"() {
> given:
> def streamOfEmptyCollections = [[]].stream()
> when:
> def flattened =
> streamOfEmptyCollections.flatMap(List::stream).toList()
> then:
> flattened == []
> }
> {code}
> But on Groovy 4 it fails with the following error:
> {noformat}
> Condition not satisfied:
> flattened == []
> | |
> | false
> [interface java.util.List]
> {noformat}
> I believe that this regression was introduced by [this change to
> {{groovy.lang.MetaClassImpl.invokeMethodClosure()}}|https://github.com/apache/groovy/commit/22e5f3bb1823041f9b0445d8e1de0c02dfa87fd1#diff-c28986077bdc1a71b46273a2f3596d89d4608fadc5843b56ec0bc25894e19652R1084]
> which was part of the fix for GROOVY-10057.
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