Regenerate adexchangebuyer client

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

2020-04-03 03:37:22,905 synthtool > Executing /tmpfs/src/git/autosynth/working_repo/synth.py.
2020-04-03 03:37:22,919 synthtool > Cloning https://github.com/googleapis/discovery-artifact-manager.git.
2020-04-03 03:37:23,535 synthtool > Cleaning output directory.
2020-04-03 03:37:23,537 synthtool > Installing dependencies.
2020-04-03 03:37:25,325 synthtool > Generating adexchangebuyer v1.2.
2020-04-03 03:37:25,325 synthtool > 	1.30.1
Writing json metadata to clients/google-api-services-adexchangebuyer/v1.2.metadata.json
2020-04-03 03:37:25,869 synthtool > Generating adexchangebuyer v1.3.
2020-04-03 03:37:25,869 synthtool > 	1.30.1
Writing json metadata to clients/google-api-services-adexchangebuyer/v1.3.metadata.json
2020-04-03 03:37:26,748 synthtool > Generating adexchangebuyer2 v2beta1.
2020-04-03 03:37:26,748 synthtool > 	1.30.1
WARNING:root:object without properties CancelNegotiationRequest: OrderedDict([(u'description', u'Request to cancel an ongoing negotiation.'), (u'type', u'object'), (u'properties', OrderedDict()), (u'id', u'CancelNegotiationRequest')])
WARNING:root:object without properties CompleteSetupRequest: OrderedDict([(u'properties', OrderedDict()), (u'id', u'CompleteSetupRequest'), (u'description', u"Request message for indicating that the proposal's setup step is complete."), (u'type', u'object')])
WARNING:root:object without properties Empty: OrderedDict([(u'properties', OrderedDict()), (u'id', u'Empty'), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated\nempty messages in your APIs. A typical example is to use it as the request\nor the response type of an API method. For instance:\n\n    service Foo {\n      rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty);\n    }\n\nThe JSON representation for `Empty` is empty JSON object `{}`.'), (u'type', u'object')])
WARNING:root:object without properties ResumeProposalRequest: OrderedDict([(u'description', u'Request message to resume (unpause) serving for an already-finalized\nproposal.'), (u'type', u'object'), (u'properties', OrderedDict()), (u'id', u'ResumeProposalRequest')])
WARNING:root:object without properties StopWatchingCreativeRequest: OrderedDict([(u'id', u'StopWatchingCreativeRequest'), (u'description', u'A request for stopping notifications for changes to creative Status.'), (u'type', u'object'), (u'properties', OrderedDict())])
Writing json metadata to clients/google-api-services-adexchangebuyer2/v2beta1.metadata.json
2020-04-03 03:37:29,059 synthtool > Generating adexchangebuyer v1.4.
2020-04-03 03:37:29,059 synthtool > 	1.30.1
Writing json metadata to clients/google-api-services-adexchangebuyer/v1.4.metadata.json
2020-04-03 03:37:30,688 synthtool > Wrote metadata to clients/google-api-services-adexchangebuyer/synth.metadata.