Bug 7914 Cannot copy a Java project in the packages view
There is no way to copy a Java project in the packages view. You can copy a project in the Navigator. This is a functional gap.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/reorg/ReorgDestinationAction.java
private ReorgRefactoring fRefactoring;
		
		public ReorgSelectionValidator(ReorgRefactoring refactoring) {
			Assert.isNotNull(refactoring);
			fRefactoring= refactoring;
		}
		
		public IStatus validate(Object[] selection)  {
			if (selection.length != 1)
				return new StatusInfo(IStatus.ERROR, "");
			try{	
				if (fRefactoring.isValidDestination(selection[0]))
					return new StatusInfo();
				return new StatusInfo(IStatus.ERROR, "");	
			} catch (JavaModelException e){
				ExceptionHandler.handle(e, "Exception", "Unexpected exception occurred. See log for details.");
				return new StatusInfo(IStatus.ERROR, "");
			}	
		}
	}
}