ActiveMQMapMessage mapMessage = new ActiveMQMapMessage();
mapMessage.setString("String", "String");
mapMessage.clearBody();
assertFalse(mapMessage.isReadOnlyBody());
mapMessage.onSend();
mapMessage.setContent(mapMessage.getContent());
assertNull(mapMessage.getString("String"));
mapMessage.clearBody();
mapMessage.setString("String", "String");