Truffle : Source code in build/contracts/HelloWorld.json doesn't change after first migrate

Question

build/contracts/HelloWorld.json

line 890:

"source": "// SPDX-License-Identifier: MIT\r\npragma solidity 0.8.7;\r\n\r\ncontract HelloWorld{\r\n function hello() public pure returns(string memory){\r\n return 'hello world';\r\n }\r\n}",

I wrote that code at start, in contracts/HelloWorld.sol ,than i changed it:

HelloWorld.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;

contract HelloWorld{

    string public message;

    constructor(string memory _message){
        message = _message;
    }


    function hello() public view returns(string memory){
        return message; 
    }

    function setMessage(string memory _message) public{
        message = _message;
    }

}

migrations/2_hello_world_migration.js

const HelloWorld = artifacts.require("HelloWorld");

module.exports = function (deployer) {
  deployer.deploy(HelloWorld,"Hello world constructor");
};

when im typing

1. truffle compile
2. truffle develop
3. migrate
4. let instance = await HelloWorld.deployed()
5. instance.hello() -> returning me 'hello world', from first build/migration
6. instance.message() -> Uncaught TypeError: instance.message is not a function
7. instance.setMessage('blah') -> Uncaught TypeError: instance.setMessage is not a function

Answer 1

truffle compile --all.

Or just try to delete the filepath build/