code: public static boolean isContainmentProxy(DatabindContext ctxt, EObject owner, EObject contained) {
  		if (contained.eIsProxy())
  			return true;
  
  		Resource ownerResource = EMFContext.getResource(ctxt, owner);
  		Resource containedResource = EMFContext.getResource(ctxt, contained);
  
  		return ownerResource != null && ownerResource != containedResource;
  	}
docs: Checks that the contained object is in a different resource than it's owner, making
  it a contained proxy.
  
  @param owner
  @param contained
  @return true if proxy