Github user kinow commented on the issue: https://github.com/apache/commons-lang/pull/275 Back to WIP. Please avoid merging it for now. Gilles noted in the mailing list that the Observable/Observer classes have been deprecated in Java 9. So we will probably go with the deprecation/removal path instead. Link to the discussion in the mailing list: https://markmail.org/message/efy52lul5pzbznut
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