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Then non-pom-packaging POMs will be published in Maven repositories as consumer POM (v4) but pom-packaging POMs will be published in Maven repositories as build POM only (eventually using new version/format): this use case won't cause issues.

POM File name

Consumer POM file name does not really have a meaning, but if it had, it would remaing as pom.xml.

Build POM file name, while updating POM format, could be changed to something like build.xml, build.pom, or even build.json or build.yaml.

Consumer POM fields

First step is to define which fields from POM v4 we want to keep in consumer POM: removed, kept because required, kept by choice (could be removed if we decide)

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