Improve formatting of schema

In YAML, null is interpreted as a literal null value,
but we intended to use it as the string "null".

For consistency the first element of the array was also formatted
in double quotes and the array is now also formatted across
multiple lines.

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

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:

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:

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

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