code: public JTSGeometryExpression<Geometry> convexHull() {
          if (convexHull == null) {
              convexHull = JTSGeometryExpressions.geometryOperation(SpatialOps.CONVEXHULL, mixin);
          }
          return convexHull;
      }
docs: Returns a geometric object that represents the convex hull of this geometric object.
  Convex hulls, being dependent on straight lines, can be accurately represented in linear
  interpolations for any geometry restricted to linear interpolations.
  
  @return convex hull