```json
{
	"yes": ["yes"],
	"no": ["no"]
}
```
Based on the given feature "foreign_worker" and the target task of whether a person receives a credit or not, it appears that the feature "foreign_worker" has a direct relationship with the target variable. If the value of "foreign_worker" is "yes", it indicates that the person is a foreign worker and they may receive a credit. On the other hand, if the value of "foreign_worker" is "no", it indicates that the person is not a foreign worker and they may not receive a credit. 

Since the categories of "foreign_worker" are pre-defined as "yes" and "no", there are no other possible values for this feature. Therefore, for the target class "yes", the possible values of "foreign_worker" are ["yes"], and for the target class "no", the possible values of "foreign_worker" are ["no"].