 Improve encapsulation on BreakInvariantBounty  (#1267)
 Improve encapsulation on BreakInvariantBounty  (#1267)

* Improve encapsulation on BreakInvariantBounty

* Make researchers private

* Do not prefix getters

OpenZeppelin/zep-solidity,OpenZeppelin/zeppelin-solidity,OpenZeppelin/zep-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/openzeppelin-contracts