private static Set<String> collectIntersectionPrefixes(FieldInfo fi)
      throws IOException {
    if (fi != null) {
      Set<String> result = new HashSet<>();
      String intersectingPrefixes = fi.getAttribute(
          MtasCodecPostingsFormat.MTAS_FIELDINFO_ATTRIBUTE_PREFIX_INTERSECTION);
      if (intersectingPrefixes != null) {
        String[] prefixes = intersectingPrefixes
            .split(Pattern.quote(MtasToken.DELIMITER));
        for (int i = 0; i < prefixes.length; i++) {
          String item = prefixes[i].trim();
          if (!item.equals("")) {
            result.add(item);
          }
        }
      }
      return result;
    } else {
      return Collections.emptySet();
    }
  }
private static Set < String > collectIntersectionPrefixes ( FieldInfo fi ) throws IOException { if ( fi != null ) { Set < String > result = new HashSet < > ( ) ; String intersectingPrefixes = fi . getAttribute ( MtasCodecPostingsFormat . MTAS_FIELDINFO_ATTRIBUTE_PREFIX_INTERSECTION ) ; if ( intersectingPrefixes != null ) { String [ ] prefixes = intersectingPrefixes . split ( Pattern . quote ( MtasToken . DELIMITER ) ) ; for ( int i = 0 ; i < prefixes . length ; i ++ ) { String item = prefixes [ i ] . trim ( ) ; if ( ! item . equals ( "" ) ) { result . add ( item ) ; } } } return result ; } else { return Collections . emptySet ( ) ; } }
Collect intersection prefixes.

@param fi
the fi
@return the sets the
@throws IOException
Signals that an I/O exception has occurred.