message: Fix dropdown usage in cluster update dialog
  The `Dropdown` component doesn't accept an array of values. It must be
  an object.
  Fixes
diff: @@ -24,15 +24,27 @@ class ClusterUpdateModal extends PromiseComponent<ClusterUpdateModalProps, Clust
  constructor(public props: ClusterUpdateModalProps) {
  super(props);
  - this.state.selectedVersion = 0;
  + const available = getAvailableClusterUpdates(props.cv);
  + this.state.selectedVersion = _.get(available, '[0].version', '');
  }
  - _submit = (e) => {
  + _submit = (e: React.FormEvent<EventTarget>) => {
  e.preventDefault();
  - const {cv} = this.props;
  const {selectedVersion} = this.state;
  - const desiredUpdate = getAvailableClusterUpdates(cv)[selectedVersion];
  - const patch = [{ op: 'add', path: '/spec/desiredUpdate', value: desiredUpdate }];
  + if (!selectedVersion) {
  + return;
  + }
  + const {cv} = this.props;
  + const available = getAvailableClusterUpdates(cv);
  + const desired = _.find(available, { version: selectedVersion });
  + if (!desired) {
  + this.setState({errorMessage: `Version ${selectedVersion} not found among the available updates. Select another version.`});
  + return;
  + }
  +
  + // Clear any previous error message.
  + this.setState({errorMessage: ''});
  + const patch = [{ op: 'add', path: '/spec/desiredUpdate', value: desired }];
  this.handlePromise(k8sPatch(ClusterVersionModel, cv, patch)).then(this.props.close);
  }
  @@ -40,7 +52,7 @@ class ClusterUpdateModal extends PromiseComponent<ClusterUpdateModalProps, Clust
  this.props.close();
  }
  - _change = (selectedVersion) => {
  + _change = (selectedVersion: string) => {
  this.setState({selectedVersion});
  }
  @@ -49,7 +61,10 @@ class ClusterUpdateModal extends PromiseComponent<ClusterUpdateModalProps, Clust
  const {selectedVersion} = this.state;
  const availableUpdates = getAvailableClusterUpdates(cv);
  const currentVersion = getDesiredClusterVersion(cv);
  - const dropdownItems = _.map(availableUpdates, 'version');
  + const dropdownItems = _.reduce(availableUpdates, (acc, {version}) => {
  + acc[version] = version;
  + return acc;
  + }, {});
  return <form onSubmit={this._submit} name="form" className="modal-content modal-content--no-inner-scroll">
  <ModalTitle>Update Cluster</ModalTitle>
  <ModalBody>
  @@ -84,7 +99,7 @@ type ClusterUpdateModalProps = {
  } & ModalComponentProps;
  type ClusterUpdateModalState = {
  - selectedVersion: number;
  + selectedVersion: string;
  inProgress: boolean;
  errorMessage: string;
  };
  