Hi @wgpubs,
if you just pass labels  the decoder_input_ids  are prepared inside the model by shifting the labels. See
  
      github.com
  
  
    huggingface/transformers/blob/cbe63949d76efd153a1f389f38fe9ce1287e06b0/src/transformers/models/bart/modeling_bart.py#L1229-L1231 9

if decoder_input_ids is None:    decoder_input_ids = shift_tokens_right(labels, self.config.pad_token_id)