marketplace-image.json does not validate w/packer 1.8.3

[wspeirs]

I just cloned the repo and attempted to validate the JSON script, and got a handful of errors:

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 9:
   9:   "sensitive-variables": ["do_token"],

No argument or block type is named "sensitive-variables".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 10:
  10:   "builders": [

No argument or block type is named "builders".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 21:
  21:   "provisioners": [

No argument or block type is named "provisioners".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 9:
   9:   "sensitive-variables": ["do_token"],

No argument or block type is named "sensitive-variables".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 10:
  10:   "builders": [

No argument or block type is named "builders".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 21:
  21:   "provisioners": [

No argument or block type is named "provisioners".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 9:
   9:   "sensitive-variables": ["do_token"],

No argument or block type is named "sensitive-variables".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 10:
  10:   "builders": [

No argument or block type is named "builders".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 21:
  21:   "provisioners": [

No argument or block type is named "provisioners".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 9:
   9:   "sensitive-variables": ["do_token"],

No argument or block type is named "sensitive-variables".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 10:
  10:   "builders": [

No argument or block type is named "builders".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 21:
  21:   "provisioners": [

No argument or block type is named "provisioners".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 9:
   9:   "sensitive-variables": ["do_token"],

No argument or block type is named "sensitive-variables".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 10:
  10:   "builders": [

No argument or block type is named "builders".

Error: Extraneous JSON object property

  on marketplace-image.pkr.json line 21:
  21:   "provisioners": [

No argument or block type is named "provisioners".