Document behavior of absent Splunk sourcetype in Custom Destinations (DataDog#3236)

Co-authored-by: ci.datadog-api-spec <packages@datadoghq.com>

Author: api-clients-generation-pipeline[bot]

.generator/schemas/v2/openapi.yaml

@@ -18679,9 +18679,10 @@ components:
           description: |-
             The Splunk sourcetype for the events sent to this Splunk destination.
 
-            If absent, the default sourcetype `_json` is used. If set to null, the `sourcetype`
-            field is omitted from the Splunk HEC payload entirely. Otherwise, the provided string
-            value is used as the sourcetype.
+            If the field is absent from the request and no sourcetype has been previously set on this destination, the default sourcetype `_json` is used.
+            On update, if the field is absent from the request but a sourcetype was previously set, the previous value is kept.
+            If set to `null`, the sourcetype field is omitted from the forwarded event entirely.
+            Otherwise, the provided string value is used as the sourcetype.
           example: my-source
           nullable: true
           type: string
@@ -18964,9 +18965,10 @@ components:
           description: |-
             The Splunk sourcetype for the events sent to this Splunk destination.
 
-            If absent, the default sourcetype `_json` is used. If set to null, the `sourcetype`
-            field is omitted from the Splunk HEC payload entirely. Otherwise, the provided string
-            value is used as the sourcetype.
+            If the field is absent from the request and no sourcetype has been previously set on this destination, the default sourcetype `_json` is used.
+            On update, if the field is absent from the request but a sourcetype was previously set, the previous value is kept.
+            If set to `null`, the sourcetype field is omitted from the forwarded event entirely.
+            Otherwise, the provided string value is used as the sourcetype.
           example: my-source
           nullable: true
           type: string

lib/datadog_api_client/v2/models/custom_destination_forward_destination_splunk.rb

@@ -30,9 +30,10 @@ class CustomDestinationForwardDestinationSplunk
 
     # The Splunk sourcetype for the events sent to this Splunk destination.
     #
-    # If absent, the default sourcetype `_json` is used. If set to null, the `sourcetype`
-    # field is omitted from the Splunk HEC payload entirely. Otherwise, the provided string
-    # value is used as the sourcetype.
+    # If the field is absent from the request and no sourcetype has been previously set on this destination, the default sourcetype `_json` is used.
+    # On update, if the field is absent from the request but a sourcetype was previously set, the previous value is kept.
+    # If set to `null`, the sourcetype field is omitted from the forwarded event entirely.
+    # Otherwise, the provided string value is used as the sourcetype.
     attr_accessor :sourcetype
 
     # Type of the Splunk HTTP Event Collector (HEC) destination.

lib/datadog_api_client/v2/models/custom_destination_response_forward_destination_splunk.rb

@@ -27,9 +27,10 @@ class CustomDestinationResponseForwardDestinationSplunk
 
     # The Splunk sourcetype for the events sent to this Splunk destination.
     #
-    # If absent, the default sourcetype `_json` is used. If set to null, the `sourcetype`
-    # field is omitted from the Splunk HEC payload entirely. Otherwise, the provided string
-    # value is used as the sourcetype.
+    # If the field is absent from the request and no sourcetype has been previously set on this destination, the default sourcetype `_json` is used.
+    # On update, if the field is absent from the request but a sourcetype was previously set, the previous value is kept.
+    # If set to `null`, the sourcetype field is omitted from the forwarded event entirely.
+    # Otherwise, the provided string value is used as the sourcetype.
     attr_accessor :sourcetype
 
     # Type of the Splunk HTTP Event Collector (HEC) destination.