Minor A document contains blobs and it is export. Reading the blob fails in JCR because file backing binary value is not found and finaly JCRBlobInputStream throws NPE. The exporter doesn't export the metadata and blobs, the import won't be able to import it.
The NPE has to be avoided. If the blobs are not available, export document without them: first remove the blob reference in the schemes and after export document XML.
