reqType, bucketName, test.objectName, err)
					}
					// Validate whether the error has occurred for the expected reason.
					if want.Code != errXML.Code {
						t.Errorf("%s, Expected to fail with error \"%s\", but received \"%s\": %q.",
							reqType, want.Code, errXML.Code, errXML.Message)
					}

         * guarantee behavior in that case, anyway, and the current behavior is likely undesirable.
         * So that's either a reason to feel free to change it or a reason to not bother thinking
         * further about this.
         */
        V rightValue = uncheckedCastNullableTToT(onlyOnRight.remove(leftKey));