I have created a lightning:dualListbox for my community page. The multi-select picklist is working normally. But the options available are not displaying in a single column.

I am trying to display the options in a column vertically below each other in Available and Selected columns respectively.

There seems to be some problem with UI , when I try to use import wizard (trail-
Developer Beginner 
Data Management 
U
Import Data)
the map button itslef doesnt appear and the system is struck. There is no way t map column or go back. Attached is screen shot.

I am beginner :  Not able to solve Trailhead challange for-Developer Beginner :Process Automation-Automate Basic Business Processes with Process Builder
"
Create a process to update child record when the parent is updated.
You've been given a requirement to keep Contact addresses in sync with the Account they belong to. Use Process Builder to create a new process that updates all child Contact addresses when the address of the Account record is updated. This process:
Can have any name.
Must be activated.
Must update Contact mailing address fields (Street, City, State, Post Code, Country) when the parent Account shipping address field values are updated.
NOTE: You may have to deactivate the validation rule for the Contacts object (created from a previous challenge) in order to complete this challenge."

 What I had tried 
Deleted validation rule on contact  from previous challange.
 Using Process builder created new Process with below details
Object: Account
Criteria:'Update Address' with condidtion

Field: selected shipping street, city, state,postalcode and country
Operator: Ischanged
Type: boolean
value: true

Condition:
Any condition met (OR)

 For Immediate action
Action name: Mailing address change
Records: Account.contacts
Criteria for Updating Records:No criteria—just update the records!

Set new field values for the records you update:

Field: selected Mailing street, city, state,postalcode and country
Type: Reference
value:  selected shipping street, city, state,postalcode and country

 after this saved and activated. So Once I check challange got below error:
"Challenge Not yet complete... here's what's wrong:
An update to an account record failed to update the mailing address fields of all child contact records. Make sure that the process is correct and that it is activated."

So Please help.





 

Create an Apex class that returns a list of contacts based on two incoming parameters: one for the number of contacts to generate, and the other for the last name. The list should NOT be inserted into the system, only returned. The first name should be dynamically generated and should be unique for each contact record in the list.The Apex class must be called 'RandomContactFactory' and be in the public scope.
The Apex class should NOT use the @isTest annotation.
The Apex class must have a public static method called 'generateRandomContacts' (without the @testMethod annotation).
The 'generateRandomContacts' method must accept an integer as the first parameter, and a string as the second. The first parameter controls the number of contacts being generated, the second is the last name of the contacts generated.
The 'generateRandomContacts' method should have a return type of List<Contact>.
The 'generateRandomContacts' method must be capable of consistently generating contacts with unique first names.
For example, the 'generateRandomContacts' might return first names based on iterated number (i.e. 'Test 1','Test 2').
The 'generateRandomContacts' method should not insert the contact records into the database.

I create a class as bellow

public class RandomContactFactory{
   public static List<Contact> generateRandomContacts(integer n,string lastnames){

       list<contact> c= [select  FirstName from contact where LastName =: lastnames limit : n ];
       
       return c;
   }
   
}

but i'm getting error as below

Challenge not yet complete... here's what's wrong: 
Executing the 'generateRandomContacts' method failed. Either the method does not exist, is not static, or did not return the correct set of Contact records.

Please let me know where the issue?