* Fix missing default value of form param
* Update php sample with OAS2
* Update php sample with OAS3
* Delete quotes as default value may have integer
* Update php samples with OAS2
* use toDefaultValue() in order to apply the decoration rules of generator
* Update php samples with OAS2
* Tweak: add quotes only if example is null
* Update php sample with OAS2
* Update php sample with OAS3
* Update php client with OAS3
* Fix content type
the endpoint consumes 'application/x-www-form-urlencoded'
* Regenerate php client from OAS3
* Update the test case according to the fix on spec