SuppressReadReceipt nullchecks after using the object

[Noblebrown]

The constructor for SuppressReadReceipt takes an argument of an Item. It will call super(Item.getService()), and then it will null check the Item on the next line. This is pointless as an Exception will be thrown when invoking super() if the Item is null.

[vboctor]

@Noblebrown I've submitted a pull request to fix the issue, please review. Thanks.