[BUG][CSHARP][PHP] Could not process model 'Dog.Type'

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

When types with an allOf definition have names with ".Type" or ".Any" suffix, there is an error at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:470)

Actual Output

[main] ERROR o.o.codegen.utils.ModelUtils - Failed to obtain schema from null
[main] ERROR o.o.codegen.utils.ModelUtils - Failed to obtain schema from null
Exception in thread "main" java.lang.RuntimeException: Could not process model 'Dog.Any'.Please make sure that your schema is correct!
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:470)
        at org.openapitools.codegen.DefaultGenerator.generate(DefaultGenerator.java:919)
        at org.openapitools.codegen.cmd.Generate.run(Generate.java:396)
        at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:60)
Caused by: java.lang.NullPointerException
        at org.openapitools.codegen.languages.AbstractPhpCodegen.toModelName(AbstractPhpCodegen.java:402)
        at org.openapitools.codegen.DefaultCodegen.fromModel(DefaultCodegen.java:1755)
        at org.openapitools.codegen.DefaultGenerator.processModels(DefaultGenerator.java:1196)
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:465)
        ... 3 more

Expected Output

• No errors

openapi-generator version

4.0.2-SNAPSHOT

OpenAPI declaration file content or url

https://gist.github.com/amiller-ims/21f6a4ec6acbb408774f629cdaf8b42c

Command line used for generation

Both of these command lines cause similar errors:

• java -jar openapi-generator-cli.jar generate -g php -i petstore.yaml
• java -jar openapi-generator-cli.jar generate -g csharp -i petstore.yaml

Steps to reproduce

1. Add ".Type" or ".Any" to the types with allOf definitions (maybe any suffix with a period "."). For example, rename "Pet" to "Pet.Type":

definitions:
  Dog.Type:
    allOf:
      - $ref: '#/definitions/Pet.Type'
      - type: object
        properties:
          breed:
            type: string

Related issues/PRs

I searched both Issues and PRs but could not find this problem.

Suggest a fix

1. Specify the full component path in InlineModelResolver.flattenComposedChildren.

Currently:

Schema schema = new Schema().$ref(innerModelName);

Proposed:

Schema schema = new Schema().$ref("#/components/schemas/" + innerModelName);

2. Change set$ref in Schema.class to check for hash ("#") instead of period ("."):

Currently:

    public void set$ref(String $ref) {
        if ($ref != null && ($ref.indexOf(".") == -1 && $ref.indexOf("/") == -1)) {
            $ref = "#/components/schemas/" + $ref;
        }
        this.$ref = $ref;
    }

Proposed:

    public void set$ref(String $ref) {
        if ($ref != null && ($ref.indexOf("#") == -1 && $ref.indexOf("/") == -1)) {
            $ref = "#/components/schemas/" + $ref;
        }
        this.$ref = $ref;
    }

Start with InlineModelResolver.flattenComposedChildren and set$ref in Schema.class, then reproduce the failure using the linked petstore.yaml and the PHP or C# generation commands. Trace how allOf schemas named with ".Type" or ".Any" are resolved and verify that both generators complete without errors.