Address PR review comments on StickyMetaParamsMiddleware

Drop the redundant autoclass description and unused module directive
in the docs, remove the stale module-level docstring, fix __init__
to properly call super().__init__(crawler) instead of skipping it,
simplify the meta copy with setdefault, and use build_from_crawler
in the test helper for consistency.

docs/topics/spider-middleware.rst

@@ -455,14 +455,7 @@ StartSpiderMiddleware
 StickyMetaParamsMiddleware
 --------------------------
 
-.. module:: scrapy.spidermiddlewares.stickymeta
-   :synopsis: Sticky Meta Params Spider Middleware
-
-.. autoclass:: StickyMetaParamsMiddleware
-
-   Allows copying some request metadata into follow-up requests automatically.
-
-   See the :setting:`STICKY_META_KEYS` setting.
+.. autoclass:: scrapy.spidermiddlewares.stickymeta.StickyMetaParamsMiddleware
 
 
 UrlLengthMiddleware

scrapy/spidermiddlewares/stickymeta.py

@@ -1,9 +1,3 @@
-"""
-Sticky Meta Params Spider Middleware
-
-See documentation in docs/topics/spider-middleware.rst
-"""
-
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
@@ -27,7 +21,8 @@ class StickyMetaParamsMiddleware(BaseSpiderMiddleware):
     Keys already present in a follow-up request are not overwritten.
     """
 
-    def __init__(self, sticky_meta_keys: list[str]):  # pylint: disable=super-init-not-called
+    def __init__(self, crawler: Crawler, sticky_meta_keys: list[str]):
+        super().__init__(crawler)
         self.sticky_meta_keys: list[str] = sticky_meta_keys
 
     @classmethod
@@ -35,7 +30,7 @@ class StickyMetaParamsMiddleware(BaseSpiderMiddleware):
         sticky_meta_keys = crawler.settings.getlist("STICKY_META_KEYS")
         if not sticky_meta_keys:
             raise NotConfigured
-        return cls(sticky_meta_keys)
+        return cls(crawler, sticky_meta_keys)
 
     def get_processed_request(
         self, request: Request, response: Response | None
@@ -43,6 +38,6 @@ class StickyMetaParamsMiddleware(BaseSpiderMiddleware):
         if response is None:
             return request
         for key in self.sticky_meta_keys:
-            if key in response.meta and key not in request.meta:
-                request.meta[key] = response.meta[key]
+            if key in response.meta:
+                request.meta.setdefault(key, response.meta[key])
         return request

tests/test_spidermiddleware_stickymeta.py

@@ -18,7 +18,7 @@ TEST_URL = "http://www.example.com"
 
 def _make_mw(sticky_meta_keys: Any) -> StickyMetaParamsMiddleware:
     crawler = get_crawler(Spider, {"STICKY_META_KEYS": sticky_meta_keys})
-    return StickyMetaParamsMiddleware.from_crawler(crawler)
+    return build_from_crawler(StickyMetaParamsMiddleware, crawler)
 
 
 async def _run_all_paths(