code: public static NewGTFSError forEntity(Entity entity, NewGTFSErrorType errorType) {
          NewGTFSError error = new NewGTFSError(entity.getClass(), errorType);
          error.lineNumber = entity.id;
          error.entityId = entity.getId();
          error.entitySequenceNumber = entity.getSequenceNumber();
          return error;
      }
docs: Factory Builder for cases where the entity has already been decoded and an error is discovered during validation