@Override
    public boolean equals(Object that) {
      if (that instanceof ChunkMetadata) {
        ChunkMetadata thatCM = (ChunkMetadata) that;
        return storeKey.equals(thatCM.storeKey) && offset == thatCM.offset && size == thatCM.size;
      }
      return false;
    }
POJO class for holding a store key, the size of the data content it refers to,
and the offset of the data in the larger composite blob
ambry-messageformat/src/main/java/com/github/ambry/messageformat/CompositeBlobInfo.java