Significant fields: equals does not use foo, or it is stateless

The cause for this error message is usually that the foo field is not used in the class’s equals contract: hence, “equals does not use foo”.

In this case, the error can be fixed by simply including foo in your equals and hashCode methods; or if this is intentional, you can suppress Warning.ALL_FIELDS_SHOULD_BE_USED or call .withIgnoredFields.

This error message can also occur when foo is included, but it is of a type with no state. A stateless type is a type that has no fields (or derives its equals method directly from Object without overriding it.) In this case, the only way to make the error go away is to suppress Warning.ALL_FIELDS_SHOULD_BE_USED or to call .withIgnoredFields.

See also the chapter on ignoring fields in the manual.