feat(genai): update model examples and enhance field descriptions in _BaseGoogleGenerativeAI (#1174)

Also make `api_transport` an alias to `transport`

Author: mdrxy

libs/genai/langchain_google_genai/_common.py

@@ -23,7 +23,7 @@ class _BaseGoogleGenerativeAI(BaseModel):
         ...,
         description="""The name of the model to use.
 Examples:
-    - gemini-2.5-pro
+    - gemini-2.5-flash
     - models/text-bison-001""",
     )
     """Model name to use."""
@@ -32,26 +32,35 @@ class _BaseGoogleGenerativeAI(BaseModel):
     )
     """Google AI API key.
     If not specified will be read from env var ``GOOGLE_API_KEY``."""
+
     credentials: Any = None
     "The default custom credentials (google.auth.credentials.Credentials) to use "
     "when making API calls. If not provided, credentials will be ascertained from "
     "the GOOGLE_API_KEY envvar"
+
     temperature: float = 0.7
-    """Run inference with this temperature. Must be within ``[0.0, 2.0]``."""
+    """Run inference with this temperature. Must be within ``[0.0, 2.0]``. If unset,
+    will default to ``0.7``."""
+
     top_p: Optional[float] = None
     """Decode using nucleus sampling: consider the smallest set of tokens whose
-       probability sum is at least ``top_p``. Must be within ``[0.0, 1.0]``."""
+    probability sum is at least ``top_p``. Must be within ``[0.0, 1.0]``."""
+
     top_k: Optional[int] = None
     """Decode using top-k sampling: consider the set of ``top_k`` most probable tokens.
-       Must be positive."""
+    Must be positive."""
+
     max_output_tokens: Optional[int] = Field(default=None, alias="max_tokens")
     """Maximum number of tokens to include in a candidate. Must be greater than zero.
-       If unset, will default to ``64``."""
+    If unset, will default to ``64``."""
+
     n: int = 1
     """Number of chat completions to generate for each prompt. Note that the API may
-       not return the full ``n`` completions if duplicates are generated."""
+    not return the full ``n`` completions if duplicates are generated."""
+
     max_retries: int = 6
-    """The maximum number of retries to make when generating."""
+    """The maximum number of retries to make when generating. If unset, will default
+    to ``6``."""
 
     timeout: Optional[float] = None
     """The maximum number of seconds to wait for a response."""
@@ -66,6 +75,7 @@ class _BaseGoogleGenerativeAI(BaseModel):
     transport: Optional[str] = Field(
         default=None,
         description="A string, one of: [`rest`, `grpc`, `grpc_asyncio`].",
+        alias="api_transport",
     )
     additional_headers: Optional[Dict[str, str]] = Field(
         default=None,