code: public BooleanExpression isEmpty() {
          if (empty == null) {
              empty = Expressions.booleanOperation(SpatialOps.IS_EMPTY, mixin);
          }
          return empty;
      }
docs: Returns 1 (TRUE) if this geometric object is the empty Geometry. If true, then this
  geometric object represents the empty point set ∅ for the coordinate space.
  
  @return empty