private static FileEntry defaultLayerEntry(Path source, AbsoluteUnixPath destination) {
    return new FileEntry(
        source,
        destination,
        FileEntriesLayer.DEFAULT_FILE_PERMISSIONS_PROVIDER.get(source, destination),
        FileEntriesLayer.DEFAULT_MODIFICATION_TIME);
  }
Gets the size of {@code blob}.

@param blob the {@link Blob}
@return the size (in bytes) of {@code blob}
@throws IOException if an I/O exception occurs
jib-core/src/test/java/com/google/cloud/tools/jib/cache/CacheTest.java