Test that footer is not written when record is empty (#543)

This commit fails and so shows that, although the record is empty,
the footer is written.

metafacture-biblio/src/test/java/org/metafacture/biblio/marc21/MarcXmlEncoderTest.java

@@ -389,4 +389,11 @@ public void shouldNotEncodeNestedTypeLiteralAsAttribute() {
         assertEquals(expected, actual);
     }
 
+    @Test
+    public void issue543_shouldNotWriteFooterWhenRecordIsEmpty() {
+        encoder.closeStream();
+        String actual = resultCollector.toString();
+        assertTrue(actual.isEmpty());
+    }
+
 }