Just an FYI, for others joining late, it's not a "drop in replacement" in anyway for Toplink Essentials. It appears to work at the JPA level, but if you used any Toplink Essentials code, it's a complete do over.
For example, we use the Toplink ExpressionBuilder classes, and we could not "drop in" the EclipseLink on top of this, minimally due to completely different package names, but even the apis were different when we tried to fix the packages.
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