protected void validate() throws IllegalStateException {
checkState(identity != null, "identity must not be null");
checkState(!local || (identity instanceof OwnIdentity),
"can not create local Sone from remote identity");
checkState(lastUpdated > 0, "last update time must be set");
protected void validate() throws IllegalStateException {
checkState(identity != null, "identity must not be null");
checkState(!local || (identity instanceof OwnIdentity),
"can not create local Sone from remote identity");
checkState(lastUpdated > 0, "last update time must be set");