A schema containing nullable is not being parsed properly when using flatten parse option

[cvgaviao]

In a 3.0 spec I have this schema:

components:
  schemas:
    User:
      type: object
      properties:
        address:
          type: object
          nullable: true
          readony: true
          properties:
            city:
              type: string

When I parse this spec with a default parser option I get this User object:

User=class ObjectSchema {
    class Schema {
        type: object
        format: null
        $ref: null
        description: null
        title: null
        multipleOf: null
        maximum: null
        exclusiveMaximum: null
        minimum: null
        exclusiveMinimum: null
        maxLength: null
        minLength: null
        pattern: null
        maxItems: null
        minItems: null
        uniqueItems: null
        maxProperties: null
        minProperties: null
        required: [address]
        not: null
        properties: {address=class ObjectSchema {
            class Schema {
                type: object
                format: null
                $ref: null
                description: null
                title: null
                multipleOf: null
                maximum: null
                exclusiveMaximum: null
                minimum: null
                exclusiveMinimum: null
                maxLength: null
                minLength: null
                pattern: null
                maxItems: null
                minItems: null
                uniqueItems: null
                maxProperties: null
                minProperties: null
                required: null
                not: null
                properties: {city=class StringSchema {
                    class Schema {
                        type: string
                        format: null
                        $ref: null
                        description: null
                        title: null
                        multipleOf: null
                        maximum: null
                        exclusiveMaximum: null
                        minimum: null
                        exclusiveMinimum: null
                        maxLength: null
                        minLength: null
                        pattern: null
                        maxItems: null
                        minItems: null
                        uniqueItems: null
                        maxProperties: null
                        minProperties: null
                        required: null
                        not: null
                        properties: null
                        additionalProperties: null
                        nullable: null
                        readOnly: null
                        writeOnly: null
                        example: null
                        externalDocs: null
                        deprecated: null
                        discriminator: null
                        xml: null
                    }
                }}
                additionalProperties: false
                nullable: true
                readOnly: true
                writeOnly: null
                example: null
                externalDocs: null
                deprecated: true
                discriminator: null
                xml: null
            }
        }}
        additionalProperties: null
        nullable: null
        readOnly: null
        writeOnly: null
        example: null
        externalDocs: null
        deprecated: null
        discriminator: null
        xml: null
    }
}

But parsing the spec using the following options then the nullable and others are null:

        ParseOptions po = new ParseOptions();
        po.setFlatten(true);
        po.setFlattenComposedSchemas(true);
        po.setResolve(true);
        po.setCamelCaseFlattenNaming(true);

Note that because of the flatten option, the parser is creating a schema named User_address:

User=class ObjectSchema {
    class Schema {
        type: object
        format: null
        $ref: null
        description: null
        title: null
        multipleOf: null
        maximum: null
        exclusiveMaximum: null
        minimum: null
        exclusiveMinimum: null
        maxLength: null
        minLength: null
        pattern: null
        maxItems: null
        minItems: null
        uniqueItems: null
        maxProperties: null
        minProperties: null
        required: [address]
        not: null
        properties: {address=class Schema {
            type: null
            format: null
            $ref: #/components/schemas/User_address
            description: null
            title: null
            multipleOf: null
            maximum: null
            exclusiveMaximum: null
            minimum: null
            exclusiveMinimum: null
            maxLength: null
            minLength: null
            pattern: null
            maxItems: null
            minItems: null
            uniqueItems: null
            maxProperties: null
            minProperties: null
            required: null
            not: null
            properties: null
            additionalProperties: null
            nullable: null
            readOnly: null
            writeOnly: null
            example: null
            externalDocs: null
            deprecated: null
            discriminator: null
            xml: null
        }}
        additionalProperties: null
        nullable: null
        readOnly: null
        writeOnly: null
        example: null
        externalDocs: null
        deprecated: null
        discriminator: null
        xml: null
    }
}

The User_address:

User_address=class Schema {
    type: object
    format: null
    $ref: null
    description: null
    title: null
    multipleOf: null
    maximum: null
    exclusiveMaximum: null
    minimum: null
    exclusiveMinimum: null
    maxLength: null
    minLength: null
    pattern: null
    maxItems: null
    minItems: null
    uniqueItems: null
    maxProperties: null
    minProperties: null
    required: null
    not: null
    properties: {city=class StringSchema {
        class Schema {
            type: string
            format: null
            $ref: null
            description: null
            title: null
            multipleOf: null
            maximum: null
            exclusiveMaximum: null
            minimum: null
            exclusiveMinimum: null
            maxLength: null
            minLength: null
            pattern: null
            maxItems: null
            minItems: null
            uniqueItems: null
            maxProperties: null
            minProperties: null
            required: null
            not: null
            properties: null
            additionalProperties: null
            nullable: null
            readOnly: null
            writeOnly: null
            example: null
            externalDocs: null
            deprecated: null
            discriminator: null
            xml: null
        }
    }}
    additionalProperties: null
    nullable: null
    readOnly: null
    writeOnly: null
    example: null
    externalDocs: null
    deprecated: null
    discriminator: null
    xml: null
}

[cvgaviao]

@gracekarina , while I was debugging in order to fix this issue I also find out that camelCaseFlattenNaming was not being properly respected. I have fixed it too.

[gracekarina]

Hi @cvgaviao thanks for submiting this PR, I have to do some tests before merging.

[cvgaviao]

@gracekarina, any news about your tests? :)