error while converting from nt to rdf/xml format in Jena - jena

Question

What is the meaning of the following error message:
I am attempting to convert the dogfood.nt to its rdf/xml representation form, what does the StackOverflow message indicate ?
<j.12:Person rdf:about="http://data.semanticweb.org/person/rich-keller">
<j.12:name>Rich Keller</j.12:name>
<rdfs:label>Rich Keller</rdfs:label>
<j.3:affiliation rdf:resource="http://data.semanticweb.org/organization/nasa-ames-research-center"/>
<j.4:holdsRole rdf:resource="http://data.semanticweb.org/conference/iswc/2005/pc-member-at-iswc2005-research-track"/>
</j.12:PersException in thread "main" java.lang.StackOverflowError
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4568)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4568)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717)
at java.util.regex.Pattern$Curly.match0(Pattern.java:4272)
at java.util.regex.Pattern$Curly.match(Pattern.java:4234)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
at java.util.regex.Pattern$Branch.match(Pattern.java:4604)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658)
at java.util.regex.Pattern$Branch.match(Pattern.java:4604)
at java.util.regex.Pattern$Branch.match(Pattern.java:4602)
Following is the code snippet used:
Model model11 = ModelFactory.createDefaultModel();
InputStream is1 = FileManager.get().open("dogfood4.nt");
if (is1 != null) {
model11.read(is1, null, "N-TRIPLE");
model11.write(os1, "RDF/XML");
} else {
System.err.println("cannot read file ");;
}
I am using the semantic dogfood n-triples.