docs: public static final <T> T getSingle( Iterable<T> it ) {
          if( ! it.iterator().hasNext() )
              return null;
  
          final Iterator<T> iterator = it.iterator();
          T o = iterator.next();
          if(iterator.hasNext())
              throw new IllegalStateException("Found multiple items in iterator over " + o.getClass().getName() );
  
          return o;
      }