[DOCS] Fix nullable type linting error in OpenAPI document (#18018) (#18021)

(cherry picked from commit 34a7c67)

Co-authored-by: Lisa Cawley <lcawley@elastic.co>

Author: mergify[bot]

docs/static/spec/openapi/logstash-api.yaml

@@ -1702,11 +1702,9 @@ components:
           type: string
           description: A unique identifier for the ephemeral session of the Logstash instance.
         snapshot:
-          type: boolean
-          nullable: true
+          type: [boolean, 'null']
         status:
           $ref: '#/components/schemas/Status'
-
     PipelineSettings:
       type: object
       properties:
@@ -2217,19 +2215,16 @@ components:
           type: object
           properties:
             last_error:
-              type: string
-              nullable: true
+              type: [ string, 'null']
             successes:
               type: integer
               format: int64
             last_success_timestamp:
-              type: string
+              type: [ string, 'null']
               format: date-time
-              nullable: true
             last_failure_timestamp:
-              type: string
+              type: [ string, 'null']
               format: date-time
-              nullable: true
             failures:
               type: integer
               format: int64

docs/static/spec/openapi/redocly.yaml

@@ -26,15 +26,10 @@ rules:
  # Paths
   no-ambiguous-paths: warn
   no-identical-paths: error
-  path-excludes-patterns:
-    severity: error
-    patterns:
-      - ^\/internal
  # Responses
   operation-4xx-response: off
   operation-2xx-response: off
  # Schema
-  spec: off
   spec-strict-refs: off
  # Tags
   operation-tag-defined: off
@@ -49,4 +44,11 @@ rules:
     severity: warn
     assertions:
       maxLength: 45
-      minLength: 5
+      minLength: 5
+  rule/path-exclude-pattern:
+    subject:
+      type: Paths
+    message: Do not include internal APIs
+    assertions:
+      notPattern: ^\/internal
+    severity: error