Old renderer with :request: emits a sourcecode block without a trailing blank line, warning under -W

When the old (default) httpdomain renderer is used with :request:, it emits a .. sourcecode:: json block for the request body and then the next field with no blank line between them. That's invalid reStructuredText, so docutils warns. Under sphinx-build -W the warning is fatal, which makes :request: unusable for projects that build with warnings as errors.

Minimal reproducer

spec.yml:

openapi: 3.0.3
info:
  title: Minimal
  version: 1.0.0
paths:
  /thing:
    post:
      summary: Create thing
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                name:
                  type: string
      responses:
        200:
          description: Created.

index.rst:

Page
====

.. openapi:: spec.yml
   :request:

conf.py:

extensions = ["sphinxcontrib.openapi"]

Actual

$ sphinx-build -W -b html src out
src/index.rst:15: WARNING: Explicit markup ends without a blank line; unexpected unindent. [docutils]

Build fails (exit 1). Without -W it's a warning and the page still renders.

Expected

No warning. The generated markup should be valid reStructuredText.

Cause

In sphinxcontrib/openapi/openapi30.py, the request-body branch emits the directive and its content but never a closing blank line:

309:            yield '{indent}**Request body:**'.format(**locals())
310:            yield ''
311:            yield '{indent}.. sourcecode:: json'.format(**locals())
312:            yield ''
313:            for line in req_properties.splitlines():
314:                # yield indent + line
315:                yield '{indent}{indent}{line}'.format(**locals())
316:                # yield ''

The next thing yielded is the :status ...: field at the outer indent level, so docutils sees the directive body end without a blank line and reports the unindent.

Note line 316: the yield '' that would close the block is present but commented out. Compare the response-example path around lines 244-248, which does emit a trailing blank line and doesn't produce this warning:

244:            yield ''
245:            for example_line in example['value'].splitlines():
246:                yield '{extra_indent}{indent}{example_line}'.format(**locals())
247:            if example['value'].splitlines():
248:                yield ''

So the fix looks like emitting a single blank line after the request-body loop, mirroring that pattern. I'm happy to open a PR if that's the direction you'd want.

Environment

• sphinxcontrib-openapi 0.9.0
• sphinxcontrib-httpdomain 2.0.0
• Sphinx 8.2.3
• docutils 0.21.2
• Python 3.12.13

Start in sphinxcontrib/openapi/openapi30.py around the request-body branch at lines 309-316, then compare it with the response-example path around lines 244-248. Run the minimal reproducer with sphinx-build -W; done means the generated request-body markup produces no docutils warning and the build succeeds.