### 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)

for marker in item.iter_markers(name="system"):
        systems_name = marker.args[0]
        if systems_name in selected_systems or "all" in selected_systems:
            return
    pytest.skip(
        f"The test is skipped because it does not have the right system marker. "
        f"Only tests marked with pytest.mark.system(SYSTEM) are run with SYSTEM "
        f"being one of {selected_systems}. {item}"
    )
def skip_system_test(item):
    for marker in item.iter_markers(name="system"):
        pytest.skip(
            f"The test is skipped because it has system marker. System tests are only run when "
            f"--system flag with the right system ({marker.args[0]}) is passed to pytest. {item}"
        )
def skip_long_running_test(item):
    for _ in item.iter_markers(name="long_running"):
        pytest.skip(
            f"The test is skipped because it has long_running marker. "
            f"And --include-long-running flag is not passed to pytest. {item}"
        )
def skip_quarantined_test(item):
    for _ in item.iter_markers(name="quarantined"):
        pytest.skip(
            f"The test is skipped because it has quarantined marker. "
            f"And --include-quarantined flag is passed to pytest. {item}"
        )
def skip_if_integration_disabled(marker, item):