groovy/groovy-core — pull request #101 by PascalSchumacher (2013-01-01 12:45:35+00:00)
Title: GROOVY-4572: Provide File method to get directory size

https://jira.codehaus.org/browse/GROOVY-4572

Original patch created by Evgeny Goldin. I just ported the patch to 2.0 and did some minimal refactoring. All credit belongs to Evgeny Goldin.