public boolean isOverridable(String fieldName) {
        FieldDescription field = getField(fieldName);
        if (field == null) return true;
        return field.isOverridable();
    }
Returns whether the given field name is overridable in this type.
Default: true (so all non-declared fields returns true)
container-search/src/main/java/com/yahoo/search/query/profile/types/QueryProfileType.java