use AppendJoin

Author: SimonCropp

src/Cake.Core/Extensions/MethodInfoExtensions.cs

@@ -41,7 +41,7 @@ public static string GetSignature(this MethodInfo method,
                 signature = isParams ? string.Concat("params ", signature) : signature;
                 parameterList[i] = signature;
             }
-            builder.Append(string.Join(", ", parameterList));
+            builder.AppendJoin(", ", parameterList);
             builder.Append(")");
             return builder.ToString();
         }

src/Cake.Core/Scripting/CodeGen/MethodAliasGenerator.cs

@@ -170,7 +170,7 @@ private static void BuildGenericArguments(MethodInfo method, StringBuilder build
             {
                 genericArguments.Add(argument.Name);
             }
-            builder.Append(string.Join(", ", genericArguments));
+            builder.AppendJoin(", ", genericArguments);
             builder.Append('>');
         }