code: public JTSGeometryExpression<Geometry> buffer(double distance) {
          return JTSGeometryExpressions.geometryOperation(SpatialOps.BUFFER, mixin, ConstantImpl.create(distance));
      }
docs: Returns a geometric object that represents all Points whose distance from this geometric
  object is less than or equal to distance. Calculations are in the spatial reference system
  of this geometric object. Because of the limitations of linear interpolation, there will
  often be some relatively small error in this distance, but it should be near the resolution
  of the coordinates used.
  
  @param distance distance
  @return buffer