Fix interface impl

src/Discord.Net.Core/Discord.Net.Core.xml

@@ -5667,9 +5667,19 @@
                 A select menu for picking from choices
             </summary>
         </member>
+        <member name="T:Discord.IMessageComponent">
+            <summary>
+                Represents a message component on a message.
+            </summary>
+        </member>
         <member name="P:Discord.IMessageComponent.Type">
             <summary>
-                The <see cref="T:Discord.ComponentType"/> of this Message Component.
+                Gets the <see cref="T:Discord.ComponentType"/> of this Message Component.
+            </summary>
+        </member>
+        <member name="P:Discord.IMessageComponent.CustomId">
+            <summary>
+                Gets the custom id of the component if possible; otherwise <see langword="null"/>.
             </summary>
         </member>
         <member name="T:Discord.MessageComponent">

src/Discord.Net.Rest/API/Common/ActionRowComponent.cs

@@ -33,5 +33,8 @@ namespace Discord.API
                 }
             }).ToArray();
         }
+
+        [JsonIgnore]
+        string IMessageComponent.CustomId => null;
     }
 }

src/Discord.Net.Rest/API/Common/ButtonComponent.cs

@@ -30,7 +30,6 @@ namespace Discord.API
         [JsonProperty("disabled")]
         public Optional<bool> Disabled { get; set; }
 
-
         public ButtonComponent() { }
 
         public ButtonComponent(Discord.ButtonComponent c)
@@ -62,5 +61,8 @@ namespace Discord.API
                 }
             }
         }
+
+        [JsonIgnore]
+        string IMessageComponent.CustomId => this.CustomId.GetValueOrDefault();
     }
 }