Billing new Py path

[lmazuel]

Latest improvements:

MSFT employees can try out our new experience at OpenAPI Hub - one location for using our validation tools and finding your workflow.

Contribution checklist:

• I have reviewed the documentation for the workflow.
• Validation tools were run on swagger spec(s) and have all been fixed in this PR.
• The OpenAPI Hub was used for checking validation status and next steps.

ARM API Review Checklist

• Service team MUST add the "WaitForARMFeedback" label if the management plane API changes fall into one of the below categories.
• adding/removing APIs.
• adding/removing properties.
• adding/removing API-version.
• adding a new service in Azure.

Failure to comply may result in delays for manifest application. Note this does not apply to data plane APIs.

• If you are blocked on ARM review and want to get the PR merged urgently, please get the ARM oncall for reviews (RP Manifest Approvers team under Azure Resource Manager service) from IcM and reach out to them.
  Please follow the link to find more details on API review process.

[AutorestCI]

Automation for azure-sdk-for-ruby

Encountered a Subprocess error: (azure-sdk-for-ruby)

Command: ['/usr/local/bin/autorest', '/tmp/tmpmjz2id97/rest/specification/billing/resource-manager/readme.md', '--perform-load=false', '--swagger-to-sdk', '--output-artifact=configuration.json', '--input-file=foo', '--output-folder=/tmp/tmpch7nwidl']
Finished with return code 7
and output:

AutoRest code generation utility [version: 2.0.4283; node: v8.12.0]
(C) 2018 Microsoft Corporation.
https://aka.ms/autorest
Failure:
Error: Unable to start AutoRest Core from /root/.autorest/@microsoft.azure_autorest-core@2.0.4370/node_modules/@microsoft.azure/autorest-core
Error: Unable to start AutoRest Core from /root/.autorest/@microsoft.azure_autorest-core@2.0.4370/node_modules/@microsoft.azure/autorest-core
    at main (/opt/node_modules/autorest/dist/app.js:232:19)
    at <anonymous>

/root/.autorest/@microsoft.azure_autorest-core@2.0.4370/node_modules/@microsoft.azure/autorest-core/dist/app.js:33
    autorest_core_1.Shutdown();
    ^
ReferenceError: autorest_core_1 is not defined
    at process.on (/root/.autorest/@microsoft.azure_autorest-core@2.0.4370/node_modules/@microsoft.azure/autorest-core/dist/app.js:33:5)
    at emitOne (events.js:121:20)
    at process.emit (events.js:211:7)
    at process.emit (/node_modules/source-map-support/source-map-support.js:439:21)
fs.js:612
  return binding.close(fd);
                 ^

Error: EBADF: bad file descriptor, close
    at Object.fs.closeSync (fs.js:612:18)
    at StaticVolumeFile.shutdown (/opt/node_modules/autorest/dist/static-loader.js:352:10)
    at StaticFilesystem.shutdown (/opt/node_modules/autorest/dist/static-loader.js:406:17)
    at process.exit.n [as exit] (/opt/node_modules/autorest/dist/static-loader.js:169:11)
    at printErrorAndExit (/node_modules/source-map-support/source-map-support.js:423:11)
    at process.emit (/node_modules/source-map-support/source-map-support.js:435:16)
    at process._fatalException (bootstrap_node.js:391:26)

[AutorestCI]

Automation for azure-sdk-for-python

The initial PR has been merged into your service PR:
Azure/azure-sdk-for-python#3853

[azuresdkci]

Can one of the admins verify this patch?

[AutorestCI]

Automation for azure-sdk-for-go

The initial PR has been merged into your service PR:
Azure/azure-sdk-for-go#4849

[AutorestCI]

Automation for azure-sdk-for-js

Nothing to generate for azure-sdk-for-js

[AutorestCI]

Automation for azure-sdk-for-java

Nothing to generate for azure-sdk-for-java