Update service/openapi.yaml

Co-authored-by: Todd Baert <todd.baert@dynatrace.com>
Signed-off-by: Jonathan Norris <jonathan.norris@dynatrace.com>

Author: jonathannorris

service/openapi.yaml

@@ -409,6 +409,7 @@ components:
         inactivityDelaySec:
           type: integer
           minimum: 1
+          default: 120
           description: |
             Number of seconds of client inactivity (e.g., browser tab hidden,
             mobile app backgrounded) after which the connection should be closed