fix: change to weaker type definitions

[YangJonghun]

Summary

change to weaker type definitions (partial revert commit bd74375bef2a618624c77d8be1bc0354460a502a) because current definition doesn't support below case

• dev

{
  "public": {
    "OPTIONAL1": "test",
    "REQUIRE": "false"
  }
}

• prod

{
  "public": {
    "OPTIONAL2": "test",
    "REQUIRE": "false"
  }
}

above case we met type error

Changelog

change to weaker type definitions

Test Plan