### 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)

on_failure_callback=None,
        on_retry_callback=None,
        email=None,
        with_dagrun_type=DagRunType.SCHEDULED,
        **kwargs,
    ):
        with dag_maker(dag_id, **kwargs) as dag:
            op = EmptyOperator(
                task_id=task_id,
                max_active_tis_per_dag=max_active_tis_per_dag,
                max_active_tis_per_dagrun=max_active_tis_per_dagrun,
                executor_config=executor_config,
                on_success_callback=on_success_callback,
                on_execute_callback=on_execute_callback,
                on_failure_callback=on_failure_callback,
                on_retry_callback=on_retry_callback,
                email=email,
                pool=pool,
                trigger_rule=trigger_rule,
            )
        if with_dagrun_type is not None:
            dag_maker.create_dagrun(run_type=with_dagrun_type)
        return dag, op
    return create_dag
@pytest.fixture
def create_task_instance(dag_maker, create_dummy_dag):
    """Create a TaskInstance, and associated DB rows (DagRun, DagModel, etc).
    Uses ``create_dummy_dag`` to create the dag structure.
    """
    def maker(