Move source code into "Source" folder

Source/DataLayer/EfClasses/Contributor.cs

@@ -0,0 +1,47 @@
+using System.Collections.Generic;
+using System.Linq;
+using Dinah.Core;
+
+namespace DataLayer
+{
+    public class Contributor
+	{
+		// Empty is a special case. use private ctor w/o validation
+		public static Contributor GetEmpty() => new() { ContributorId = -1, Name = "" };
+
+		// contributors search links are just name with url-encoding. space can be + or %20
+		//   author search link:   /search?searchAuthor=Robert+Bevan
+		//   narrator search link: /search?searchNarrator=Robert+Bevan
+		// can also search multiples. concat with comma before url encode
+
+		// id.s
+		// ----
+		// https://www.audible.com/author/Neil-Gaiman/B000AQ01G2 == https://www.audible.com/author/B000AQ01G2
+		//     goes to summary page
+		//     at bottom "See all titles by Neil Gaiman" goes to https://www.audible.com/search?searchAuthor=Neil+Gaiman
+		// some authors have no id. simply goes to https://www.audible.com/search?searchAuthor=Rufus+Fears
+		// all narrators have no id: https://www.audible.com/search?searchNarrator=Neil+Gaiman
+
+		internal int ContributorId { get; private set; }
+        public string Name { get; private set; }
+
+        private HashSet<BookContributor> _booksLink;
+        public IEnumerable<BookContributor> BooksLink => _booksLink?.ToList();
+
+        public string AudibleContributorId { get; private set; }
+
+        private Contributor() { }
+        public Contributor(string name, string audibleContributorId = null)
+        {
+            Name = ArgumentValidator.EnsureNotNullOrWhiteSpace(name, nameof(name));
+
+            _booksLink = new HashSet<BookContributor>();
+
+			// don't overwrite with null or whitespace but not an error
+			if (!string.IsNullOrWhiteSpace(audibleContributorId))
+				AudibleContributorId = audibleContributorId;
+		}
+
+		public override string ToString() => Name;
+	}
+}