BuildProcess/CustomModule/CustomModuleModule.cs

using CustomModule.Views;
using Prism.Ioc;
using Prism.Modularity;
using Prism.Regions;

namespace CustomModule
{
    public class CustomModuleModule : IModule
    {
        public void OnInitialized(IContainerProvider containerProvider)
        {
            var regionManager = containerProvider.Resolve<RegionManager>();
            regionManager.RegisterViewWithRegion("EditRegion", typeof(ViewA));

        }
            public void RegisterTypes(IContainerRegistry containerRegistry)
        {

        }
    }
}