code: public boolean markMigrated(VectorClock vectorClock) {
          stateWriteLock.lock();
          try {
              if (stateVectorClock.equals(vectorClock)) {
                  migrated = true;
              }
              return migrated;
          } finally {
              stateWriteLock.unlock();
          }
      }
docs: Marks this CRDT as migrated. A migrated CRDT can no longer be mutated.
  For this CRDT to be marked as migrated, the provided {@code vectorClock}
  must be equal to the current vector clock.
  
  @param vectorClock a vector clock to compare the current clock to
  @return {@code true} if this CRDT has been marked as migrated,
  {@code false} otherwise