Symfony YAML does not parse all YAML

[cebe]

While trying to add more tests for more specs from these sources:

• https://github.com/Mermade/openapi3-examples/tree/master/resources
• https://github.com/Nexmo/api-specification/tree/master/definitions
• https://github.com/APIs-guru/openapi-directory

I found that symfony YAML fails on a lot of these.
We either need an alternative YAML parser or improve symfony YAML to not fail.

• https://github.com/yaml/yaml-test-suite
• Run the Yaml parser against the Yaml testsuite symfony/symfony#27965

[cebe]

https://github.com/mustangostang/spyc/blob/master/Spyc.php

[simPod]

I've encountered the same issue. The problem is that it parses only arrays while getSerializableData() return stdClasses.

[simPod]

I'm using typical trick from js world:

Yaml::dump(
    json_decode(json_encode($openApiSpec->create()->getSerializableData()), true),
    flags: Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE
)

[cebe]

Consider allowing ext-yaml as an alternative.

#170 is a duplicate of this one.