code: public static DoubleBinding floor(final ObservableDoubleValue a) {
          return createDoubleBinding(() -> Math.floor(a.get()), a);
      }
docs: Binding for {@link java.lang.Math#floor(double)}
  
  @param   a   a value.
  @return  the largest (closest to positive infinity)
  floating-point value that less than or equal to the argument
  and is equal to a mathematical integer.