chore: remove nullable

Author: shanewxy

schema.yaml

@@ -19,15 +19,13 @@ components:
             domain_suffix:
               description: |
                 Specify the domain suffix of the CloudMap. The domain suffix must be a valid DNS name.
-              nullable: true
               title: Domain Suffix
               type: string
               x-walrus-ui:
                 order: 3
             kms_key_id:
               description: |
                 Specify the KMS key ID which to encrypt the PostgreSQL data. If not specified, the PostgreSQL data will not be encrypted.
-              nullable: true
               title: Kms Key Id
               type: string
               x-walrus-ui:
@@ -36,7 +34,6 @@ components:
               default: false
               description: |
                 Specify whether to enable public access. If enabled, the PostgreSQL service can be accessed from the public network.
-              nullable: true
               title: Publicly Accessible
               type: boolean
               x-walrus-ui:
@@ -61,7 +58,6 @@ components:
           enum:
           - standalone
           - replication
-          nullable: true
           x-walrus-ui:
             group: Basic
             order: 3
@@ -75,7 +71,6 @@ components:
           - 1
           - 3
           - 5
-          nullable: true
           x-walrus-ui:
             group: Basic
             order: 4
@@ -90,7 +85,6 @@ components:
           - "15.0"
           - "14.0"
           - "13.0"
-          nullable: true
           x-walrus-ui:
             group: Basic
             order: 5
@@ -118,7 +112,6 @@ components:
             type: object
             x-walrus-ui:
               colSpan: 12
-          nullable: true
           x-walrus-ui:
             colSpan: 12
             group: Basic
@@ -131,7 +124,6 @@ components:
             Specify the database name. The database name must be 2-64 characters long and start with any lower letter, combined with number, or symbols: - _.
             The database name cannot be PostgreSQL forbidden keyword.
           default: mydb
-          nullable: true
           minLength: 2
           maxLength: 64
           x-walrus-ui:
@@ -144,7 +136,6 @@ components:
             Specify the account username. The username must be 2-16 characters long and start with lower letter, combined with number, or symbol: _.
             The username cannot be PostgreSQL forbidden keyword and postgres.
           default: rdsuser
-          nullable: true
           minLength: 2
           maxLength: 16
           x-walrus-ui:
@@ -158,7 +149,6 @@ components:
             If not specified, it will generate a random password.
             See https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_Limits.html#RDS_Limits.Constraints.
           format: password
-          nullable: true
           writeOnly: true
           minLength: 8
           maxLength: 32
@@ -172,13 +162,11 @@ components:
             Specify the computing resources.
           default:
             class: db.t3.medium
-          nullable: true
           properties:
             class:
               default: db.t3.medium
               description: |
                 Specify the computing resources. See https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.DBInstanceClass.html#Concepts.DBInstanceClass.Summary.
-              nullable: true
               title: Class
               type: string
               x-walrus-ui:
@@ -195,13 +183,11 @@ components:
           default:
             class: gp2
             size: 20480
-          nullable: true
           properties:
             class:
               default: gp2
               description: |
                 Specify the storage class. See https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_Storage.html.
-              nullable: true
               title: Class
               type: string
               x-walrus-ui:
@@ -211,7 +197,6 @@ components:
               description: |
                 Specify the storage size. Unit is megabyte.
               minimum: 20480
-              nullable: true
               title: Size(MiB)
               type: number
               x-walrus-ui: