chore: Updatedate the doc string of LiveRequest

activity_start, activity_end , and blob is sent via send_realtime_input, according to the docstring : https://github.com/googleapis/python-genai/blob/d98c757c7d9a88026ac0f9eb2b1b578e2e7f3bfe/google/genai/live.py#L251, they should be send separately, so makes sense they are mutally exclusive.

And we already make them exclusive in our current logic:
https://github.com/google/adk-python/blob/6c0bf85042c38c7bafe1c183f1bba8bee1ba3570/src/google/adk/flows/llm_flows/base_llm_flow.py#L264-L272, make it clear in docstring

Co-authored-by: Xiang (Sean) Zhou <seanzhougoogle@google.com>
PiperOrigin-RevId: 855492864

Author: seanzhougoogle

src/google/adk/agents/live_request_queue.py

@@ -30,13 +30,29 @@ class LiveRequest(BaseModel):
   """The pydantic model config."""
 
   content: Optional[types.Content] = None
-  """If set, send the content to the model in turn-by-turn mode."""
+  """If set, send the content to the model in turn-by-turn mode.
+
+  When multiple fields are set, they are processed by priority (highest first):
+  activity_start > activity_end > blob > content.
+  """
   blob: Optional[types.Blob] = None
-  """If set, send the blob to the model in realtime mode."""
+  """If set, send the blob to the model in realtime mode.
+
+  When multiple fields are set, they are processed by priority (highest first):
+  activity_start > activity_end > blob > content.
+  """
   activity_start: Optional[types.ActivityStart] = None
-  """If set, signal the start of user activity to the model."""
+  """If set, signal the start of user activity to the model.
+
+  When multiple fields are set, they are processed by priority (highest first):
+  activity_start > activity_end > blob > content.
+  """
   activity_end: Optional[types.ActivityEnd] = None
-  """If set, signal the end of user activity to the model."""
+  """If set, signal the end of user activity to the model.
+
+  When multiple fields are set, they are processed by priority (highest first):
+  activity_start > activity_end > blob > content.
+  """
   close: bool = False
   """If set, close the queue. queue.shutdown() is only supported in Python 3.13+."""