static Map<String,List<String>> unmodifiableCopyOfExtraProperties(final Map<String,List<String>> extraProperties){
  if (extraProperties == null || extraProperties.isEmpty()) {
    return Collections.emptyMap();
  }
  final Map<String,List<String>> tmp=new LinkedHashMap<>(extraProperties.size());
  for (  final Map.Entry<String,List<String>> e : extraProperties.entrySet()) {
    tmp.put(e.getKey(),unmodifiableCopyOfList(e.getValue()));
  }
  return Collections.unmodifiableMap(tmp);
}

static Map < String , List < String > > unmodifiableCopyOfExtraProperties ( final Map < String , List < String > > extraProperties ) { if ( extraProperties == null || extraProperties . isEmpty ( ) ) { return Collections . emptyMap ( ) ; } final Map < String , List < String > > tmp = new LinkedHashMap < > ( extraProperties . size ( ) ) ; for ( final Map . Entry < String , List < String > > e : extraProperties . entrySet ( ) ) { tmp . put ( e . getKey ( ) , unmodifiableCopyOfList ( e . getValue ( ) ) ) ; } return Collections . unmodifiableMap ( tmp ) ; }
returns an unmodifiable copy of the provided schema element extra properties .
