We could simplify this method:
```java
    private void createMissingRecipientFields() throws APIException {
        final List<String> availableFields = loadAvailableFields();
        for ( RecipientField field :  config.getFields() ) {
            if ( !availableFields.contains( field.getName() ) ) {
                addField( field.getName(), field.getType() );
            }
        }
    }
```
Personally I like the `final` keyword and I hate the `this` qualifier for accessing object methods.