Consistent nullability for StringUtils array/collection input parameters [SPR-17123]

[spring-issuemaster]

rinx opened SPR-17123 and commented

Spring Framework 5.1 provides a function named StringUtils.collectionToCommaDelimitedString which is defined here:

https://github.com/spring-projects/spring-framework/blob/master/spring-core/src/main/java/org/springframework/util/StringUtils.java#L1289

has argument type "Collection<?> coll".

However, it calls collectionToDelimitedString which accepts "Nullable" collection. I think collectionToCommaDelimitedString should be able to handle "Nullable" collection.

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Affects: 5.1 RC1

Referenced from: pull request #1917, and commits 69c6a40

[spring-issuemaster]

Juergen Hoeller commented

Well spotted! In fact, there are other nullability inconsistencies in StringUtils as well. I'll revisit them combined in a larger revision for 5.1 RC2.