partners/unstructured: fix client api_url (#24680)

**Description:** Add empty string default for api_key and change
`server_url` to `url` to match existing loaders.

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from the root of the package(s) you've modified. See contribution
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- Make sure optional dependencies are imported within a function.
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If no one reviews your PR within a few days, please @-mention one of
baskaryan, efriis, eyurtsev, ccurme, vbarda, hwchase17.

libs/partners/unstructured/langchain_unstructured/document_loaders.py

@@ -88,14 +88,14 @@ class UnstructuredLoader(BaseLoader):
         # SDK parameters
         api_key: Optional[str] = None,
         client: Optional[UnstructuredClient] = None,
-        server_url: Optional[str] = None,
+        url: Optional[str] = None,
         **kwargs: Any,
     ):
         """Initialize loader."""
         if file_path is not None and file is not None:
             raise ValueError("file_path and file cannot be defined simultaneously.")
         if client is not None:
-            disallowed_params = [("api_key", api_key), ("server_url", server_url)]
+            disallowed_params = [("api_key", api_key), ("url", url)]
             bad_params = [
                 param for param, value in disallowed_params if value is not None
             ]
@@ -106,8 +106,8 @@ class UnstructuredLoader(BaseLoader):
                     f"params: {', '.join(bad_params)}."
                 )
 
-        unstructured_api_key = api_key or os.getenv("UNSTRUCTURED_API_KEY")
-        unstructured_url = server_url or os.getenv("UNSTRUCTURED_URL") or _DEFAULT_URL
+        unstructured_api_key = api_key or os.getenv("UNSTRUCTURED_API_KEY") or ""
+        unstructured_url = url or os.getenv("UNSTRUCTURED_URL") or _DEFAULT_URL
 
         self.client = client or UnstructuredClient(
             api_key_auth=unstructured_api_key, server_url=unstructured_url
@@ -165,7 +165,6 @@ class _SingleDocumentLoader(BaseLoader):
         file: Optional[IO[bytes]] = None,
         partition_via_api: bool = False,
         post_processors: Optional[list[Callable[[str], str]]] = None,
-        # SDK parameters
         **kwargs: Any,
     ):
         """Initialize loader."""