old_contents: 'use strict';
  import {Collection} from './collection';
  import {Field, Group} from '../types/all';
  
  const defaultProps = {
  	items: [],
  	theme: null,
  	themeVarName: null,
  	layout: null
  };
  
  export class InfoboxData extends Collection {
  
  	constructor(properties = {}) {
  		
  		super();
  
  		Object.assign(this, defaultProps, properties);
  		
  		if (properties.items) {
  			this.setItems(properties.items);
  		}
  	}
  
  	newField(params) {
  		return new Field(params);
  	}
  
  	newGroup(params) {
  		return new Group(params);
  	}
  
  }
  
new_contents: 'use strict';
  import {Collection} from './collection';
  import {Field, Group} from '../types/all';
  
  const defaultProps = {
  	items: [],
  	theme: null,
  	themeVarName: null,
  	layout: null
  };
  
  export class InfoboxData extends Collection {
  
  	constructor(properties = {}) {
  		
  		super();
  
  		Object.assign(this, defaultProps, properties);
  		
  		if (this.items) {
  			this.setItems(this.items);
  		}
  	}
  
  	newField(params) {
  		return new Field(params);
  	}
  
  	newGroup(params) {
  		return new Group(params);
  	}
  
  }
  
subject: fix InfoboxData constructor null param error