(DOCSP-51331) changeEvent timestamp fields (#13091)

* (DOCSP-51331) changeEvent timestamp fields

- Add warning to not modify certain expected fields

* (DOCSP-51331) Copy review.

* (DOCSP-51331) Create include

- Break change event time fields info into includes
  file.
- Reframe info as an 'important' directive

Author: lmkerbey-mdb

content/atlas/source/atlas-stream-processing/sp-agg-source.txt

@@ -1,4 +1,3 @@
-.. _streams-agg-pipeline-source:
 .. _atlas-sp-agg-source:
 
 ========================================
@@ -411,8 +410,12 @@ The ``$source`` stage takes a document with the following fields:
      - document
      - Optional
      - Specifies an aggregation pipeline to filter change stream output
-       at the point of origin. This pipeline must conform to the parameters
-       described in :manual:`Modify Change Stream Output </changeStreams/#modify-change-stream-output>`.
+       before passing it on for further processing. This pipeline must
+       conform to the parameters described in
+       :manual:`Modify Change Stream Output
+       </changeStreams/#modify-change-stream-output>`.
+
+       .. include:: /includes/atlas-stream-processing/change-event-time.rst
 
    * - ``config.maxAwaitTimeMS``
      - integer
@@ -603,6 +606,8 @@ The ``$source`` stage takes a document with the following fields:
        at the point of origin. This pipeline must conform to the parameters
        described in :manual:`Modify Change Stream Output </changeStreams/#modify-change-stream-output>`.
 
+       .. include:: /includes/atlas-stream-processing/change-event-time.rst
+
    * - ``config.maxAwaitTimeMS``
      - integer
      - Optional
@@ -779,6 +784,11 @@ The ``$source`` stage takes a document with the following fields:
        at the point of origin. This pipeline must conform to the parameters
        described in :ref:`<change-stream-modify-output>`.
 
+       Note that {+atlas-sp+} expects to receive the ``wallTime`` and
+       ``clusterTime`` fields from each ingested Change Event. To
+       ensure proper processing of Change Stream data, do not modify
+       these fields in ``$source.config.pipeline``.
+
    * - ``config.maxAwaitTimeMS``
      - integer
      - Optional

content/atlas/source/includes/atlas-stream-processing/change-event-time.rst

@@ -0,0 +1,6 @@
+.. important::
+   Each Change Event includes ``wallTime`` and ``clusterTime``
+   fields. {+atlas-sp+} stages after ``$source`` expect to receive
+   these fields as the processor ingested them. To ensure proper
+   processing of Change Stream data, do not modify these fields in
+   ``$source.config.pipeline``.