public BooleanExpression isSimple() {
        if (simple == null) {
            simple = Expressions.booleanOperation(SpatialOps.IS_SIMPLE, mixin);
        }
        return simple;
    }
Returns 1 (TRUE) if this geometric object has no anomalous geometric points, such
as self intersection or self tangency. The description of each instantiable geometric class
will include the specific conditions that cause an instance of that class to be classified as not simple.

@return simple
querydsl-spatial/src/main/java/com/querydsl/spatial/GeometryExpression.java