Bug in InlineModelResolver

Description

Logic of flattenComponents method is out of sequence. ArraySchema are not flattened.

openapi-generator version

4.0.0, but noted also in master

OpenAPI declaration file content or url

    "products":{
      "type":"array",
      "title":"List of Prodcuts",
      "description":"List of Products",
      "xml":{
        "wrapped":true
      },
      "items":{
        "type":"object",
        "title":"Product",
        "description":"Product",
        "xml":{
          "name":"product",
          "wrapped":true
        },
        "required":[
          "id",
          "qty"
        ],
        "properties":{
          "id":{
            "type":"string",
            "title":"Product Id",
            "description":"Master Product Id"
          },
          "qty":{
            "type":"number",
            "format":"float",
            "title":"Quantity",
            "description":"Number of this product being shipped at this line",
            "minimum":0.1
          },
          "freightClass":{
            "type":"string",
            "title":"Freight Class",
            "description":"Freight Class"
          },
          "weight":{
            "type":"number",
            "format":"float",
            "title":"Weight",
            "description":"Weight of single unit of measure of product"
          },
          "weightUnit":{
            "type":"string",
            "title":"Weight Unit",
            "description":"Weight Unit"
          },
          "dimLength":{
            "type":"number",
            "format":"float",
            "title":"Dimension, Length",
            "description":"Length of the product to be shipped"
          },
          "dimHeight":{
            "type":"number",
            "format":"float",
            "title":"Dimension, Height",
            "description":"Height of the product to be shipped"
          },
          "dimWidth":{
            "type":"number",
            "format":"float",
            "title":"Dimension, Width",
            "description":"Width of the product to be shipped"
          },
          "dimUnits":{
            "type":"string",
            "title":"Dimension, unit of measure",
            "description":"Unit of measure of dimensions"
          }
        }
      }
    }

Command line used for generation

N/A (Mojo)

Steps to reproduce

1. #/component/schema/ProductList is type "array"
2. Array items are an object with properties

The array item is not flattened to a $ref.

Related issues/PRs

Suggest a fix/enhancement

Since an ArraySchema is also a Schema, this sequence doesn't work.
} else if (model instanceof Schema) {
Schema m = (Schema) model;
Map<String, Schema> properties = m.getProperties();
flattenProperties(properties, modelName);
fixStringModel(m);
} else if (ModelUtils.isArraySchema(model)) {

Use this sequence instead (unless the logic for Schema should also be executed, in which case the "else" should be removed from the ArraySchema condition):
} else if (ModelUtils.isArraySchema(model)) {
final ArraySchema m = (ArraySchema) model;
final Schema inner = m.getItems();
if (inner instanceof ObjectSchema) {
System.out.printf("--- %s: found inner schema for array items%n", modelName);
final ObjectSchema op = (ObjectSchema) inner;
if (op.getProperties() != null && op.getProperties().size() > 0) {
System.out.printf("--- %s: inner schema has properties%n", modelName);
final String innerModelName = resolveModelName(op.getTitle(), modelName + "_inner");
final Schema innerModel = modelFromProperty(op, innerModelName);
final String existing = matchGenerated(innerModel);
if (existing == null) {
openAPI.getComponents().addSchemas(innerModelName, innerModel);
addGenerated(innerModelName, innerModel);
final Schema schema = new Schema().$ref(innerModelName);
schema.setRequired(op.getRequired());
m.setItems(schema);
} else {
final Schema schema = new Schema().$ref(existing);
schema.setRequired(op.getRequired());
m.setItems(schema);
}
}
}
} else if (model instanceof Schema) {

Start at InlineModelResolver.flattenComponents and reproduce the issue with the provided OpenAPI declaration, focusing on the products array and its object items. Verify that the array item is flattened to a $ref while preserving the reported schema details; the payload does not name a test file.