### 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)

print(
            "Skipping initializing of the DB as it was initialized already.\n"
            "You can re-initialize the database by adding --with-db-init flag when running tests."
        )
    integration_kerberos = os.environ.get("INTEGRATION_KERBEROS")
    if integration_kerberos == "true":
        
        kerberos = os.environ.get("KRB5_KTNAME")
        if kerberos:
            subprocess.check_call(["kinit", "-kt", kerberos, "bob@EXAMPLE.COM"])
        else:
            print("Kerberos enabled! Please setup KRB5_KTNAME environment variable")
            sys.exit(1)
def pytest_configure(config):
    config.addinivalue_line("filterwarnings", "error::airflow.utils.context.AirflowContextDeprecationWarning")
    config.addinivalue_line("markers", "integration(name): mark test to run with named integration")
    config.addinivalue_line("markers", "backend(name): mark test to run with named backend")
    config.addinivalue_line("markers", "system(name): mark test to run with named system")
    config.addinivalue_line("markers", "long_running: mark test that run for a long time (many minutes)")
    config.addinivalue_line(
        "markers", "quarantined: mark test that are in quarantine (i.e. flaky, need to be isolated and fixed)"
    )
    config.addinivalue_line(
        "markers", "credential_file(name): mark tests that require credential file in CREDENTIALS_DIR"
    )
    config.addinivalue_line(
        "markers", "need_serialized_dag: mark tests that require dags in serialized form to be present"
    )
    os.environ["_AIRFLOW__SKIP_DATABASE_EXECUTOR_COMPATIBILITY_CHECK"] = "1"
def pytest_unconfigure(config):