code: @Override
      public void addIsland(Island isl) {
          if (LOG.isLoggable(Level.FINE)) {
              LOG.log(Level.FINE, "adding island: '{0}'", isl);
          }
          for (Coordinate coordinate : isl) {
              fixedRows.set(coordinate.row);
              fixedVertices.add(coordinate.match.vertex);
          }
          fixedIslands.add(isl);
      }
docs: /*
  Commit an island
  Island will be part of the final alignment