[Javascript] Fix for constructors not handling required fields with default values well

[tray2100]

This PR is for issue #6648. I verified that the output was as expected where for a spec that contains a required field with a default value will now look like

    _this['field'] = field || 'defaultValue';

instead of just

    _this['field'] = field;

where it forces the required field to be undefined even though we have a default value. I also noticed that the samples were out of date and there wasn't a generate script for ES5 so I've added those here. I can squash the commits if needed before merging.

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project beforehand.
• Run the shell script ./bin/generate-samples.shto update all Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master. These must match the expectations made by your contribution. You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/config/java*. For Windows users, please run the script in Git BASH.
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cc: @CodeNinjai @frol @cliffano

[wing328]

@tray2100 thanks for the PR. If a field is required, there shouldn't be any default value since the value must be provided.

In other words, the default value is for the optional field, right?

[tray2100]

@tray2100 thanks for the PR. If a field is required, there shouldn't be any default value since the value must be provided.

In other words, the default value is for the optional field, right?

Hey @wing328

I probably should have shared more of my use case. I've defined a oneOf entity and made the discriminator required in the schemas referenced in it. It feels super awkward right now when using the constructFromObject mechanism because you'll have to manually add in the discriminator after the object is constructed - even if you used the entity created by the generator in the first place. It's even more awkward if there is a chain of constructFromObject calls and the entity with the discriminator is a few levels down the object graph.

Setting the field to the default value if nothing is specified solves this problem in a minimalist way.

This is essentially the spec:

 OneOfDogCat:
      oneOf:
      - $ref: "#/components/schemas/Dog"
      - $ref: "#/components/schemas/Cat"
      type: "object"
      discriminator:
        propertyName: "entityType"
 Dog:
      type: "object"
      properties:
        entityType:
          default: "dog"
          type: "string"
        name:
          type: "string"
      required:
      - "entityType"
 Cat:
      type: "object"
      properties:
        entityType:
          default: "cat"
          type: "string"
        name:
          type: "string"
      required:
      - "entityType"

[wing328]

@tray2100 as discussed we can use {{#oneOf}} .. {{/oneOf}} to further enhance this fix for oneOf models only. Let's see if the community can help out with this.