in commons-rdf-simple/src/main/java/org/apache/commons/rdf/simple/LiteralImpl.java [57:73]
public LiteralImpl(final String literal, final String languageTag) {
this.lexicalForm = Objects.requireNonNull(literal);
this.languageTag = Objects.requireNonNull(lowerCase(languageTag));
if (languageTag.isEmpty()) {
// TODO: Check against
// http://www.w3.org/TR/n-triples/#n-triples-grammar
throw new IllegalArgumentException("Language tag can't be null");
}
try {
new Locale.Builder().setLanguageTag(languageTag);
} catch (final IllformedLocaleException ex) {
throw new IllegalArgumentException("Invalid languageTag: " + languageTag, ex);
}
// System.out.println(aLocale);
this.dataType = Types.RDF_LANGSTRING;
}