Bug 12523 Paste in Packages does not accept files on the clipboard
I created a FileTransfer in another view that contains file paths and placed it on the clipboard using SWT DND Clipboard object. Resource navigator recognized this and allowed me to paste the files into the project, but Packages 'Paste' didn't.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/reorg/PasteResourcesFromClipboardAction.java
private static boolean canActivateCopyRefactoring(IResource[] resourceData, IResource selectedResource) {
		try{
			CopyRefactoring ref= createCopyRefactoring(resourceData);
			if (! ref.checkActivation(new NullProgressMonitor()).isOK())
				return false;
			return ref.isValidDestination(ClipboardActionUtil.tryConvertingToJava(selectedResource));
			
		} catch (JavaModelException e){
			return false;
		}	
	}
	
	
	
	private IResource getFirstSelectedResource(IStructuredSelection selection){
		return ClipboardActionUtil.getFirstResource(selection);
	}
	
	private IResource[] getClipboardResources() {
		return ((IResource[])fClipboard.getContents(ResourceTransfer.getInstance()));
	}
	
	private TypedSource[] getClipboardSourceReference() {
		return ((TypedSource[])fClipboard.getContents(TypedSourceTransfer.getInstance()));
	}
	private static CopyRefactoring createCopyRefactoring(IResource[] resourceData) {
		return new CopyRefactoring(ClipboardActionUtil.getConvertedResources(resourceData), new CopyQueries());
	}
}