- **Constants classes**: Same pattern

### Argument Validation

Use `AssertionUtil` at method entry:
- `AssertionUtil.assertArgumentNotNull("argName", value)`
- `AssertionUtil.assertArgumentNotEmpty("argName", value)`

### Exception Handling

- Wrap checked exceptions in runtime exceptions from `org.codelibs.core.exception`
- Use error codes (e.g., "ECL0008" = null argument)

                "loc": ["body", "grant_type"],
                "msg": "Field required",
                "input": None,
            }
        ]
    }


@pytest.mark.parametrize(
    argnames=["grant_type"],
    argvalues=[
        pytest.param("incorrect", id="incorrect value"),
        pytest.param("passwordblah", id="password with suffix"),
        pytest.param("blahpassword", id="password with prefix"),

                "loc": ["body", "grant_type"],
                "msg": "Field required",
                "input": None,
            }
        ]
    }


@pytest.mark.parametrize(
    argnames=["grant_type"],
    argvalues=[
        pytest.param("incorrect", id="incorrect value"),
        pytest.param("passwordblah", id="password with suffix"),
        pytest.param("blahpassword", id="password with prefix"),

                "loc": ["body", "grant_type"],
                "msg": "Field required",
                "input": None,
            }
        ]
    }


@pytest.mark.parametrize(
    argnames=["grant_type"],
    argvalues=[
        pytest.param("incorrect", id="incorrect value"),
        pytest.param("passwordblah", id="password with suffix"),
        pytest.param("blahpassword", id="password with prefix"),