I've been doing some more thinking about this. I think UtilValidate.isEmpty() should work with an array, as Jacques said. Currently it doesn't.
There is at least one spot where isEmpty is being used with an array: https://fisheye6.atlassian.com/browse/ofbiz/trunk/specialpurpose/ebaystore/src/org/ofbiz/ebaystore/EbayStore.java?hb=true#to1441
That is very misleading code. Anyone reading it would be entitled to assume isEmpty would test for null and for an empty array.
If we do want to support arrays, and we want to remove UtilValidate.isEmpty for any Object in general, then we need to add eight overloaded versions of UtilValidate.isEmpty for arrays of each of the primitive types, plus one more for Object.
Is that OK in order to achieve the goal of this Jira, or should we give up on compile time checking of calls to isEmpty?