[BUG][PHP] Missing tagged union discriminator literal

[brianferri]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The PHP Client Generator doesn't generate all available discriminator options

in Params.php (after generation) we get:

    public const SERVICE_PROP0 = 'Prop0';

    /**
     * Gets allowable values of the enum
     *
     * @return string[]
     */
    public function getServiceAllowableValues()
    {
        return [
            self::SERVICE_PROP0,
        ];
    }

when we should instead be seeing:

    public const SERVICE_PROP0 = 'Prop0';
    public const SERVICE_PROP1 = 'Prop1';

    /**
     * Gets allowable values of the enum
     *
     * @return string[]
     */
    public function getServiceAllowableValues()
    {
        return [
            self::SERVICE_PROP0,
            self::SERVICE_PROP1,
        ];
    }

openapi-generator version

npm: "@openapitools/openapi-generator-cli": "^2.15.3",
jar: 7.10.0

OpenAPI declaration file content or url

Untitled-1.json
https://dpaste.org/k2Qoe

Generation Details

openapitools.config.yml

generatorName: php-nextgen
outputDir: core/client
globalProperties:
  models: ""
  apis: ""
  supportingFiles: "README.md,ApiException.php,Configuration.php,HeaderSelector.php,ObjectSerializer.php,ModelInterface.php"

openapi-generator-cli generate -i Untitled-1.json -c openapitools.config.yml

Steps to reproduce

Generate the php-nextgen client using the command, configuration and json (as an example) provided above

Related issues/PRs

Suggest a fix

It seems the issue has to do with these lines:

openapi-generator/modules/openapi-generator/src/main/resources/php-nextgen/model_generic.mustache

Lines 193 to 216 in 289425b

	{{#vars}}
	{{#isEnum}}
	{{#allowableValues}}
	{{#enumVars}}
	public const {{enumName}}_{{{name}}} = {{{value}}};
	{{/enumVars}}
	{{/allowableValues}}
	{{/isEnum}}
	{{/vars}}
	{{#vars}}
	{{#isEnum}}
	/**
	* Gets allowable values of the enum
	*
	* @return string[]
	*/
	public function {{getter}}AllowableValues()
	{
	return [
	{{#allowableValues}}{{#enumVars}}self::{{enumName}}_{{{name}}},{{^-last}}
	{{/-last}}{{/enumVars}}{{/allowableValues}}
	];
	}

Probably present in other PHP client generators as well.

[brianferri]

Additionally it would seem that, with the same setup as above, the lines:

openapi-generator/modules/openapi-generator/src/main/resources/php-nextgen/model_generic.mustache

Lines 243 to 247 in 289425b

	{{#discriminator}}
	// Initialize discriminator property with the model name.
	$this->container['{{discriminatorName}}'] = static::$openAPIModelName;
	{{/discriminator}}

Interfere with the construction of the Params object:
Params.php

public function __construct(array $data = null)
    {
        $this->setIfExists('service', $data ?? [], 'Prop0');
        $this->setIfExists('prop1', $data ?? [], null);
        $this->setIfExists('prop0', $data ?? [], null);

        // Initialize discriminator property with the model name.
        $this->container['service'] = static::$openAPIModelName; // Overwrites the `setIfExists` above
    }