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You can start by moving project.xml to pom.xml, change pomVersion to modelVersion in the table bellow and than follow some of the mappings (bold letters denote elements that need to be changed).
The alternative to the table is to use NetBeans and do XML validation, which will give you which elements need correction according to the new XML schema.
The following table resulted from conversion of project.xml in pom.xml of the org-glast-groupmanager project. Mappings between project.xml and pom.xml elements:
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