Eek, anonymize scattered all over this file makes it hard to track what should and should not be anonymized.  I'd create a Set of anonymous fields and let writeElement() figure out if it should anonymize or not.

```java
private static final Set<String> privateFields = ImmutableSet<String>.of(HOST_ELEMENT, POST_ELEMENT, etc);

// In writeElement()
if(privateFields.contains(elementName)) { 
    value = ANNON_STRING;
}
```