@JsonProperty("join")
        public void setPrimaryConnection(String primaryConnection) {
            this.primaryConnection = primaryConnection;
        }
Sets the opaque ID of the connection being joined (shared). If
specified, any provided protocol is ignored. This is exposed via the
"join" property within JSON.

@param primaryConnection
    The opaque ID of the connection being joined (shared).
extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/user/UserData.java