{
  "GroupId":"@TGS#_@TGS#cQVLVHIM62CJ",// Group of the topic to be modified, which is required
  "TopicId":"@TGS#_@TGS#cQVLVHIM62CJ@TOPIC#_@TOPIC#cRTE3HIM62C5",// ID of the topic to be modified, which is required
  "TopicName":"TestTopicName",// Topic name, which is optional
  "Notification":"Notification"    // Topic notice, which is optional
}

{
  "GroupId":"@TGS#_@TGS#cQVLVHIM62CJ",	// Group of the topic to be modified, which is required
  "TopicId":"@TGS#_@TGS#cQVLVHIM62CJ@TOPIC#_@TOPIC#cRTE3HIM62C5",	// ID of the topic to be modified, which is required
  "From_Account":"1400187352",	// Member modifying the topic
  "TopicName":"TestTopicName",// Topic name, which is optional
  "FaceUrl": "http://this.is.new.face.url", // Topic profile photo, which is optional
  "Notification":"Notification",    // Topic notice, which is optional
  "Introduction": "Introduction",// Topic introduction, which is optional
  "MuteAllMember": "On", // Mutes all members, which is optional. `On`: Enable. `Off`: Disable 
  "CustomString":"This is a customs string." // Custom string, which is optional
}