	function checkObj(instance,objTypeDef,path,additionalProp){

		if(typeof objTypeDef =='object'){
			if(typeof instance != 'object' || instance instanceof Array){
				errors.push({property:path,message:"an object is required"});
			}
			
			for(var i in objTypeDef){ 
				if(objTypeDef.hasOwnProperty(i) && i != '__proto__'){
					var value = instance[i];
					// skip _not_ specified properties
					if (value === undefined && options.existingOnly) continue;
					var propDef = objTypeDef[i];
					// set default
					if(value === undefined && propDef["default"]){
						value = instance[i] = propDef["default"];
					}
					if(options.coerce && i in instance){
						value = instance[i] = options.coerce(value, propDef);
					}
					checkProp(value,propDef,path,i);
				}
			}
		}
		for(i in instance){
			if(instance.hasOwnProperty(i) && !(i.charAt(0) == '_' && i.charAt(1) == '_') && objTypeDef && !objTypeDef[i] && additionalProp===false){
				if (options.filter) {
					delete instance[i];
					continue;
				} else {
					errors.push({property:path,message:"The property " + i +
						" is not defined in the schema and the schema does not allow additional properties"});
				}
			}
			var requires = objTypeDef && objTypeDef[i] && objTypeDef[i].requires;
			if(requires && !(requires in instance)){
				errors.push({property:path,message:"the presence of the property " + i + " requires that " + requires + " also be present"});
			}
			value = instance[i];
			if(additionalProp && (!(objTypeDef && typeof objTypeDef == 'object') || !(i in objTypeDef))){
				if(options.coerce){
					value = instance[i] = options.coerce(value, additionalProp);
				}
				checkProp(value,additionalProp,path,i);
			}
			if(!_changing && value && value.$schema){
				errors = errors.concat(checkProp(value,value.$schema,path,i));
			}
		}
		return errors;
	}
The software receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.