Add Maven 'bill-of-materials' project [SPR-11138]

[spring-projects-issues]

Rob Winch opened SPR-11138 and commented

A bill-of-materials POM would be a useful addition to Spring.

See http://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#Importing_Dependencies (search for BOM)

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Issue Links:

• Publish Spring BOM with Spring releases [SPR-10480] #15113 Publish Spring BOM with Spring releases ("supersedes")

Referenced from: commits 22ece06, 92e144a