Add custom import statements

Fixes manual addition of custom import statement for:
- UploadSession

Author: Caitlin Bales (MSFT)

Templates/Android/BaseModel.template.tt

@@ -808,4 +808,12 @@ public {1} {2}{3}{4} {{";
 
 		return property != null ? property.GetValue(customMethods).ToString() : string.Empty;
 	}
+
+	public string AddCustomImport(string className) {
+		CustomImports customImports = new CustomImports();
+		var type = customImports.GetType();
+		var property = type.GetFields().Where(x => x.Name == className).FirstOrDefault();
+
+		return property != null ? property.GetValue(customImports).ToString() : string.Empty;
+	}
 #>

src/GraphODataTemplateWriter/CodeHelpers/Android/CustomImports.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Microsoft.Graph.ODataTemplateWriter.CodeHelpers.Android
+{
+    public class CustomImports
+    {
+        public const string UploadSession = "import com.microsoft.graph.concurrency.ChunkedUploadProvider;\r\n";
+    }
+}