* @throws IOException
*/
private void readPrefixMappings(InputStream in,boolean validate) throws IOException {
LineIterator it = IOUtils.lineIterator(in, "UTF-8");
while(it.hasNext()){
String mapping = it.nextLine();
if(mapping.charAt(0) != '#'){
int sep = mapping.indexOf('\t');
if(sep < 0 || mapping.length() <= sep+1){
log.warn("Illegal prefix mapping '{}'",mapping);
} else {