ChildContactMapController.apxc

public class ChildContactMapController {
	
    @AuraEnabled
    public static List<Address> contactAddressMap(String recordId) {
        List<Address> adressList = new List<Address>();
        List<Contact> conList = [SELECT ID, Name, MailingStreet, MailingCity, MailingState, MailingCountry, MailingPostalCode from Contact 
                                	WHERE AccountID =: recordId];
        for(Contact con : conList) {
            location location = new location(con.MailingStreet, con.MailingCity,con.MailingState,con.MailingCountry,con.MailingPostalCode);
            adressList.add(new Address(location, con.Name));
        }
        return adressList;
    }
    
    public class Address {
        @AuraEnabled
        public location location;
        @AuraEnabled
        public string icon;
        @AuraEnabled
        public string title;
        @AuraEnabled
        public string description;
        
        public address(location locTemp, string titleTemp) {
            location = locTemp;
            title = titleTemp;
            icon = 'standard:contact';
        }
    }
    
    public class location {
        @AuraEnabled
        public string Street;
        @AuraEnabled
        public string City;
        @AuraEnabled
        public string PostalCode;
        @AuraEnabled
        public string State;
        @AuraEnabled
        public string Country;
        
        public location(string StreetTemp, string CityTemp, string StateTemp, string CountryTemp, string PostalCodeTemp) {
            Street = StreetTemp;
            City = CityTemp;
            PostalCode = PostalCodeTemp;
            State = StateTemp;
            Country = CountryTemp;
        }
    }
}

LightningMap.cmp

<aura:component controller="ChildContactMapController" implements="force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes" access="global">
    <!-- attributes -->
    <aura:attribute name="mapMarkers" type="Object"/>
    <aura:attribute name="center" type="Object" />
    <aura:attribute name="zoomLevel" type="Integer" />
    <aura:attribute name="markersTitle" type="String" />
    <aura:attribute name="showFooter" type="Boolean" />

    <!-- handlers-->
    <aura:handler name="init" value="{! this }" action="{! c.init }"/>

    <aura:if isTrue="{!v.mapMarkers.length > 0}" >
    <lightning:map
        mapMarkers="{! v.mapMarkers }"
        center="{! v.center }"
        zoomLevel="{! v.zoomLevel }"
        markersTitle="{! v.markersTitle }"
        showFooter="{ !v.showFooter }" >
    </lightning:map>
    </aura:if>
</aura:component>

LightningMapController.Js

({
    init: function (cmp, event, helper) {
        
		var action = cmp.get('c.contactAddressMap');
        var recordId = cmp.get('v.recordId');
		action.setParams({recordId: recordId});
		action.setCallback(this, function(response) {
        var state = response.getState();
        if (state === 'SUCCESS') {
          cmp.set('v.mapMarkers',response.getReturnValue() );
          cmp.set('v.center', {
                location: {
                    City: 'Denver'
                }
            });

          cmp.set('v.zoomLevel', 4);
          cmp.set('v.markersTitle', 'Contact Locations Marker');
          cmp.set('v.showFooter', true);
        }
        });
        $A.enqueueAction(action);
    }
})