code: public static JTSGeometryExpression<?> collect(Expression<? extends Geometry> expr1, Expression<? extends Geometry> expr2) {
          return geometryOperation(SpatialOps.COLLECT2, expr1, expr2);
      }
docs: Return a specified ST_Geometry value from a collection of other geometries.
  
  @param expr1 geometry
  @param expr2 other geometry
  @return geometry collection