old_contents: import Ember from 'ember';
  import RecordKeeperMixin from 'ember-time-machine/mixins/time-machine';
  import Record from 'ember-time-machine/-private/Record';
  import { wrapValue, unwrapValue } from 'ember-time-machine/utils/value';
  import { pathInGlobs } from 'ember-time-machine/utils/utils';
  
  export default Ember.ObjectProxy.extend(RecordKeeperMixin, {
    unknownProperty(key) {
      return wrapValue(this, key, this._super(...arguments));
    },
  
    setUnknownProperty(key, value) {
      let content = this.get('content');
      let state = this.get('_rootMachineState');
      let path = this.get('_path');
  
      if (state && !pathInGlobs(path.concat(key).join('.'), state.get('frozenProperties'))) {
        this._addRecord(new Record({
          target: content,
          path,
          key,
          before: content.get(key),
          after: value
        }));
  
        return this._super(key, unwrapValue(value));
      }
  
      this.notifyPropertyChange(key);
      return;
    }
  });
  
new_contents: import Ember from 'ember';
  import RecordKeeperMixin from 'ember-time-machine/mixins/time-machine';
  import Record from 'ember-time-machine/-private/Record';
  import { wrapValue, unwrapValue } from 'ember-time-machine/utils/value';
  import { pathInGlobs } from 'ember-time-machine/utils/utils';
  
  const { get } = Ember;
  
  export default Ember.ObjectProxy.extend(RecordKeeperMixin, {
    unknownProperty(key) {
      return wrapValue(this, key, this._super(...arguments));
    },
  
    setUnknownProperty(key, value) {
      let content = get(this, 'content');
      let state = get(this, '_rootMachineState');
      let path = get(this, '_path');
  
      if (state && !pathInGlobs(path.concat(key).join('.'), get(state, 'frozenProperties'))) {
        this._addRecord(new Record({
          target: content,
          path,
          key,
          before: get(content, key),
          after: value
        }));
  
        return this._super(key, unwrapValue(value));
      }
  
      this.notifyPropertyChange(key);
      return;
    }
  });
  
subject: Use Ember.get in Object Proxy