### Apache Airflow version

Other Airflow 2 version (please specify below)

### What happened

Airflow 2.3.4 (but actual code seems to have same behaviour).

I have mapped task with xcom value.

I want to get xcom value of particular instance or xcom values of all task instances.

I am using standard REST API method /dags/{dag_id}/dagRuns/{dag_run_id}/taskInstances/{task_id}/xcomEntries/{xcom_key}

And it throws an error
`
  File &#34;/home/airflow/.local/lib/python3.9/site-packages/sqlalchemy/orm/query.py&#34;, line 2850, in one_or_none
    return self._iter().one_or_none()
  File &#34;/home/airflow/.local/lib/python3.9/site-packages/sqlalchemy/engine/result.py&#34;, line 1510, in one_or_none
    return self._only_one_row(
  File &#34;/home/airflow/.local/lib/python3.9/site-packages/sqlalchemy/engine/result.py&#34;, line 614, in _only_one_row
    raise exc.MultipleResultsFound(
sqlalchemy.exc.MultipleResultsFound: Multiple rows were found when one or none was required
`

Is it any way of getting xcom of mapped tasks via API?

### What you think should happen instead

_No response_

### How to reproduce

Make dag with mapped task. Return xcom value in every task. Try to get xcom value via API.

### Operating System

ubuntu 20.04

### Versions of Apache Airflow Providers

_No response_

### Deployment

Other

### Deployment details

Standard

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

execution_date=None,
        dagrun_state=None,
        state=None,
        run_id=None,
        run_type=None,
        data_interval=None,
        **kwargs,
    ) -> TaskInstance:
        if execution_date is None:
            from airflow.utils import timezone
            execution_date = timezone.utcnow()
        _, task = create_dummy_dag(with_dagrun_type=None, **kwargs)
        dagrun_kwargs = {"execution_date": execution_date, "state": dagrun_state}
        if run_id is not None:
            dagrun_kwargs["run_id"] = run_id
        if run_type is not None:
            dagrun_kwargs["run_type"] = run_type
        if data_interval is not None:
            dagrun_kwargs["data_interval"] = data_interval
        dagrun = dag_maker.create_dagrun(**dagrun_kwargs)
        (ti,) = dagrun.task_instances
        ti.task = task
        ti.state = state
        dag_maker.session.flush()
        return ti
    return maker
@pytest.fixture()
def create_task_instance_of_operator(dag_maker):