public static void setBlockSize(int type, int blockSize) {
        if (managers.containsKey(type)) {
            managers.get(type).blockSize = blockSize;
        }
        else {
            new SequenceManager(type, blockSize);
        }
    }
Used to set the blocksize of a given SequenceManager. If no SequenceManager has
been registered for the type, the type is verified as valid and then a new
sequence manager is created.

@param type the type of unique id.
@param blockSize how many blocks of ids we should.
xmppserver/src/main/java/org/jivesoftware/database/SequenceManager.java