protected internal PackagePart(Package package, Uri partUri, string contentType, CompressionOption compressionOption)
{
Check.Package(package);
Check.PartUri(partUri);
Check.ContentTypeIsValid(contentType);
Package = package;
Uri = partUri;
ContentType = contentType;
CompressionOption = compressionOption;
RelationshipsPartUri = PackUriHelper.GetRelationshipPartUri(Uri);
}