docs: protected void mergeEntries(int pos1, int pos2) {
          assert (this.numFreeEntries() == 0);
          assert (pos1 < pos2);
  
          this.entries[pos1].mergeWith(this.entries[pos2]);
  
          for (int i = pos2; i < entries.length - 1; i++) {
              entries[i] = entries[i + 1];
          }
          entries[entries.length - 1].clear();
      }