Add AddRangeExpand method to BaseOptions

src/Stripe.net/Services/_base/BaseOptions.cs

@@ -35,6 +35,22 @@ public void AddExpand(string value)
             this.Expand.Add(value);
         }
 
+        /// <summary>
+        /// Adds a collection of <c>expand</c> values to the request, to request expansion of
+        /// specific fields in the response. When requesting expansions in a list request, don't
+        /// forget to prefix the field names with <c>data.</c>.
+        /// </summary>
+        /// <param name="values">The collection of names of the fields to expand.</param>
+        public void AddRangeExpand(IEnumerable<string> values)
+        {
+            if (this.Expand == null)
+            {
+                this.Expand = new List<string>();
+            }
+
+            this.Expand.AddRange(values);
+        }
+
         /// <summary>
         /// Adds an extra parameter to the request. This can be useful if you need to use
         /// parameters not available in regular options classes, e.g. for beta features.

src/Stripe.net/Services/_base/Service.cs

@@ -285,10 +285,7 @@ protected BaseOptions SetupOptions(BaseOptions options, bool isListMethod)
             }
 
             options = options ?? new BaseOptions();
-            foreach (var expansion in serviceExpansions)
-            {
-                options.AddExpand(expansion);
-            }
+            options.AddRangeExpand(serviceExpansions);
 
             return options;
         }