Optional parameters should accept None (e.g., pageToken: str | None)

[ryo-tagami]

Problem

Optional parameters (required: false in Discovery Documents) are typed as str = ... (or int = ..., etc.), but google-api-python-client accepts None for these parameters at runtime.

Example

Current stub:

def list(
    self,
    *,
    pageSize: int = ...,
    pageToken: str = ...,
    **kwargs: typing.Any,
) -> ListAccessProposalsResponseHttpRequest: ...

Actual usage that works at runtime but fails type checking:

token = get_token_from_cache()  # may return None
service.files().list(pageToken=token)  # Runtime: OK, mypy: error

Expected

def list(
    self,
    *,
    pageSize: int | None = ...,
    pageToken: str | None = ...,
    **kwargs: typing.Any,
) -> ListAccessProposalsResponseHttpRequest: ...

Root Cause

Discovery Documents define optional parameters as:

{
  "pageToken": {
    "type": "string",
    "required": false
  }
}

create_stubs.py converts "type": "string" to str and marks non-required parameters with = ..., but does not add | None to the type.

Safety Verification

I verified that this change is safe by examining google-api-python-client's implementation:

1. All API methods are generated by createMethod (except _next methods which don't take user parameters)

2. None removal is unconditionally executed in every method call:

   def method(self, **kwargs):
       # ... credential validation ...
       # ... unexpected argument check ...
       
       # None removal (always executed, no skip conditions)
       keys = list(kwargs.keys())
       for name in keys:
           if kwargs[name] is None:
               del kwargs[name]
       
       # ... required parameter check (after None removal) ...

3. Behavior by parameter type:

   • required: true + None → removed → TypeError: Missing required parameter (correctly rejected)
   • required: false + None → removed → works normally (parameter omitted from request)

Impact

This affects a large number of parameters:

• str = ...: ~16,800 occurrences
• int = ...: ~5,000 occurrences

Suggested Fix

In create_stubs.py, add | None for non-required parameters:

# Around line 213-217
type = get_type(parameter)
if parameter.get("repeated"):
    assert "_list[" not in type and type != "_list"
    type = f"{type} | _list[{type}]"
if not parameter.get("required"):  # Add this
    type = f"{type} | None"
parameters[parameter_name] = type

This change only affects required: false parameters, so type safety for required parameters is preserved.