@Override
  public int hashCode() {
    int result = digest.hashCode();
    result = 31 * result + (int) (size ^ (size >>> 32));
    return result;
  }
Checks if two {@link BlobDescriptor}s are equal.

<p>Two blobs are equal if their:

<ol>
  <li>{@code digest}s are not null and equal, and
  <li>{@code size}s are non-negative and equal
</ol>
jib-core/src/main/java/com/google/cloud/tools/jib/blob/BlobDescriptor.java