diff --git a/docs/api/apiv3/components/schemas/attachment_model.yml b/docs/api/apiv3/components/schemas/attachment_model.yml
index abb6d7f367b..b4bbf06498b 100644
--- a/docs/api/apiv3/components/schemas/attachment_model.yml
+++ b/docs/api/apiv3/components/schemas/attachment_model.yml
@@ -27,11 +27,11 @@ properties:
   status:
     type: string
     enum:
-    - uploaded
-    - prepared
-    - scanned
-    - quarantined
-    - rescan
+      - uploaded
+      - prepared
+      - scanned
+      - quarantined
+      - rescan
   contentType:
     type: string
     description: The files MIME-Type as determined by the server
diff --git a/docs/api/apiv3/components/schemas/status_model.yml b/docs/api/apiv3/components/schemas/status_model.yml
index 597896088bd..63c6c3d3553 100644
--- a/docs/api/apiv3/components/schemas/status_model.yml
+++ b/docs/api/apiv3/components/schemas/status_model.yml
@@ -17,7 +17,9 @@ properties:
     type: boolean
     description: Indicates, whether work package of this status are considered closed
   color:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: hex-code
     description: The color of the status
   isDefault:
diff --git a/docs/api/apiv3/components/schemas/user_model.yml b/docs/api/apiv3/components/schemas/user_model.yml
index 73f8640d270..99fe2cefac2 100644
--- a/docs/api/apiv3/components/schemas/user_model.yml
+++ b/docs/api/apiv3/components/schemas/user_model.yml
@@ -12,7 +12,9 @@ allOf:
         enum:
           - User
       avatar:
-        type: [string, null]
+        type:
+          - "string"
+          - "null"
         format: uri
         description: URL to user's avatar
       login:
diff --git a/docs/api/apiv3/components/schemas/version_model.yml b/docs/api/apiv3/components/schemas/version_model.yml
index 2ebbae7810a..6bff4982fa5 100644
--- a/docs/api/apiv3/components/schemas/version_model.yml
+++ b/docs/api/apiv3/components/schemas/version_model.yml
@@ -21,10 +21,14 @@ properties:
     - "$ref": "./formattable.yml"
     - {}
   startDate:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: date
   endDate:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: date
   status:
     type: string
diff --git a/docs/api/apiv3/components/schemas/work_package_model.yml b/docs/api/apiv3/components/schemas/work_package_model.yml
index 65ea7559c39..e2f9719f842 100644
--- a/docs/api/apiv3/components/schemas/work_package_model.yml
+++ b/docs/api/apiv3/components/schemas/work_package_model.yml
@@ -36,15 +36,21 @@ properties:
     type: boolean
     description: If true, the work package is in a readonly status so with the exception of the status, no other property can be altered.
   startDate:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: date
     description: Scheduled beginning of a work package
   dueDate:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: date
     description: Scheduled end of a work package
   date:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: date
     description: Date on which a milestone is achieved
   derivedStartDate:
@@ -62,18 +68,24 @@ properties:
       two dates can deviate.
     readOnly: true
   duration:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: duration
     description: |-
       **(NOT IMPLEMENTED)** The amount of time in hours the work package needs to be completed.
       Not available for milestone type of work packages.
     readOnly: true
   estimatedTime:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: duration
     description: Time a work package likely needs to be completed excluding its descendants
   derivedEstimatedTime:
-    type: [string, null]
+    type:
+      - "string"
+      - "null"
     format: duration
     description: Time a work package likely needs to be completed including its descendants
     readOnly: true
@@ -99,7 +111,9 @@ properties:
     minimum: 0
     maximum: 100
   derivedPercentageDone:
-    type: [integer, null]
+    type:
+      - "integer"
+      - "null"
     description: Amount of total completion for a work package derived from itself and its descendant work packages
     readOnly: true
     minimum: 0