BlockReceiver.complete

//line 454 of https://github.com/freenet/fred/blob/3fcc2d1b3a0d5ccbeb73928d6b267440e5b4c17b/src/freenet/io/xfer/BlockReceiver.java
    private void complete(byte[] ret) {
        synchronized(this) {
            if(completed) {
                if(logMINOR) Logger.minor(this, "Already completed");
                return;
            }
            completed = true;
        }
        _prb.removeListener(myListener);
        callback.blockReceived(ret);
        decRunningBlockReceives();
    }