code: public boolean isConnected(final Interval<C> that) {
          if(this.hasNone() || that.hasNone()) {
              return false; 
          }
          return this.range.isConnected(that.range);
      }
docs: Test if two intervals are connected
  @param that interval
  @return true if the two intervals are connected
  @see Range#isConnected(com.google.common.collect.Range)