In OpenZeppelin wird _deliverTokens() vom CrowdSale Vertrag nicht aufgerufen

Ich verwende openZeppelin für die Erstellung des ICO-Vertrags. Können Sie mir bitte helfen, das folgende Verhalten zu verstehen?

Massenverkauf

Der CrowdSale-Vertrag hat die Funktion buyTokens(). Es ruft die _processPurchase(). Der _processPurchase()ruft_deliverTokens()

MintedCrowdsale

Der MintedCrowdsale-Vertrag hat auch die Funktion_deliverTokens()

Frage : Wenn ich buyTokens()von einem CrowdSale-Vertrag aus anrufe, rufe ich an _processPurchase()und processPurchase()rufe _deliverTokens()von MintedCrowdsaleeinem Vertrag und nicht von CrowdSaleeinem Vertrag an. Könnten Sie mir bitte den Grund mitteilen.

SampleCrowdsale

contract SampleCrowdsale is FinalizableCrowdsale, MintedCrowdsale {

    event CrowdsaleFinalized();

    constructor(
    uint256 openingTime,
    uint256 closingTime,
    uint256 rate,
    address wallet,
    address secWallet, 
    ERC20Mintable token
    )
    public
    Crowdsale(rate, wallet,secWallet, token) 
    TimedCrowdsale(openingTime, closingTime) 
    { 
    }   

}

Massenverkauf

contract Crowdsale is ReentrancyGuard {
  using SafeMath for uint256;
  using SafeERC20 for IERC20;

  // The token being sold
  IERC20 private _token;

  // Address where funds are collected
  address private _wallet;

  // Address where sec % funds are collected
  address private _secWallet;

  // How many token units a buyer gets per wei.
  // The rate is the conversion between wei and the smallest and indivisible token unit.
  // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
  // 1 wei will give you 1 unit, or 0.001 TOK.
  uint256 private _rate;

  // Amount of wei raised
  uint256 private _weiRaised;

  /**
   * Event for token purchase logging
   * @param purchaser who paid for the tokens
   * @param beneficiary who got the tokens
   * @param value weis paid for purchase
   * @param amount amount of tokens purchased
   */
  event TokensPurchased(
    address indexed purchaser,
    address indexed beneficiary,
    uint256 value,
    uint256 amount
  );

  /**
   * @param rate Number of token units a buyer gets per wei
   * @dev The rate is the conversion between wei and the smallest and indivisible
   * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
   * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
   * @param wallet Address where collected funds will be forwarded to
   * @param token Address of the token being sold
   */
  constructor(uint256 rate, address wallet,address secWallet, IERC20 token) internal {
    require(rate > 0);
    require(wallet != address(0));
    require(token != address(0));

    _rate = rate;
    _wallet = wallet;
    _secWallet=secWallet;
    _token = token;
  }

  // -----------------------------------------
  // Crowdsale external interface
  // -----------------------------------------

  /**
   * @dev fallback function ***DO NOT OVERRIDE***
   * Note that other contracts will transfer fund with a base gas stipend
   * of 2300, which is not enough to call buyTokens. Consider calling
   * buyTokens directly when purchasing tokens from a contract.
   */
  function () external payable {
    buyTokens(msg.sender);
  }

  /**
   * @return the token being sold.
   */
  function token() public view returns(IERC20) {
    return _token;
  }

  /**
   * @return the address where funds are collected.
   */
  function wallet() public view returns(address) {
    return _wallet;
  }

  /**
   * @return the number of token units a buyer gets per wei.
   */
  function rate() public view returns(uint256) {
    return _rate;
  }

  /**
   * @return the amount of wei raised.
   */
  function weiRaised() public view returns (uint256) {
    return _weiRaised;
  }

  /**
   * @dev low level token purchase ***DO NOT OVERRIDE***
   * This function has a non-reentrancy guard, so it shouldn't be called by
   * another `nonReentrant` function.
   * @param beneficiary Recipient of the token purchase
   */
  function buyTokens(address beneficiary) public nonReentrant payable {

    uint256 weiAmount = msg.value;
    _preValidatePurchase(beneficiary, weiAmount);

    // calculate token amount to be created
    uint256 tokens = _getTokenAmount(weiAmount);

    // update state
    _weiRaised = _weiRaised.add(weiAmount);

    _processPurchase(beneficiary, tokens);
    emit TokensPurchased(
      msg.sender,
      beneficiary,
      weiAmount,
      tokens
    );

    _updatePurchasingState(beneficiary, weiAmount);

    _forwardFunds();
    _postValidatePurchase(beneficiary, weiAmount);
  }

// -----------------------------------------
// Internal interface (extensible)
// -----------------------------------------

/**
* @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use `super` in contracts that inherit from Crowdsale to extend their validations.
* Example from CappedCrowdsale.sol's _preValidatePurchase method:
* super._preValidatePurchase(beneficiary, weiAmount);
* require(weiRaised().add(weiAmount) <= cap);
* @param beneficiary Address performing the token purchase
* @param weiAmount Value in wei involved in the purchase
*/
function _preValidatePurchase(
address beneficiary,
uint256 weiAmount
)
internal
view
{
require(beneficiary != address(0));
require(weiAmount != 0);
}

/**
* @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
* @param beneficiary Address performing the token purchase
* @param weiAmount Value in wei involved in the purchase
*/
function _postValidatePurchase(
address beneficiary,
uint256 weiAmount
)
internal
view
{
// optional override
}

/**
* @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
* @param beneficiary Address performing the token purchase
* @param tokenAmount Number of tokens to be emitted
*/
function _deliverTokens(
address beneficiary,
uint256 tokenAmount
)
internal
{
_token.safeTransfer(beneficiary, tokenAmount);
}

/**
* @dev Executed when a purchase has been validated and is ready to be executed. Doesn't necessarily emit/send tokens.
* @param beneficiary Address receiving the tokens
* @param tokenAmount Number of tokens to be purchased
*/
function _processPurchase(
address beneficiary,
uint256 tokenAmount
)
internal
{
_deliverTokens(beneficiary, tokenAmount);
}

/**
* @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
* @param beneficiary Address receiving the tokens
* @param weiAmount Value in wei involved in the purchase
*/
function _updatePurchasingState(
address beneficiary,
uint256 weiAmount
)
internal
{
// optional override
}

/**
* @dev Override to extend the way in which ether is converted to tokens.
* @param weiAmount Value in wei to be converted into tokens
* @return Number of tokens that can be purchased with the specified _weiAmount
*/
function _getTokenAmount(uint256 weiAmount)
internal view returns (uint256)
{
return weiAmount.mul(_rate);
}

/**
* @dev Determines how ETH is stored/forwarded on purchases.
*/
function _forwardFunds() internal { 
uint256 firstAmt = msg.value.mul(9);
uint256 secAmt;
firstAmt=firstAmt.div(100); 
_wallet.transfer(firstAmt); 
secAmt=msg.value.sub(firstAmt);
_secWallet.transfer(secAmt); 
}
}

MintedCrowdsale

/**
* @title MintedCrowdsale
* @dev Extension of Crowdsale contract whose tokens are minted in each purchase.
* Token ownership should be transferred to MintedCrowdsale for minting.
*/
contract MintedCrowdsale is Crowdsale {
constructor() internal {}

/**
* @dev Overrides delivery by minting tokens upon purchase.
* @param beneficiary Token purchaser
* @param tokenAmount Number of tokens to be minted
*/
function _deliverTokens(
address beneficiary,
uint256 tokenAmount
)
internal
{
// Potentially dangerous assumption about the type of the token.
require(
ERC20Mintable(address(token())).mint(beneficiary, tokenAmount));
}
}

FinalisierbarCrowdsale

contract FinalizableCrowdsale is TimedCrowdsale {
using SafeMath for uint256;

bool private _finalized;

event CrowdsaleFinalized();

constructor() internal {
_finalized = false;
}

/**
* @return true if the crowdsale is finalized, false otherwise.
*/
function finalized() public view returns (bool) {
return _finalized;
}

/**
* @dev Must be called after crowdsale ends, to do some extra finalization
* work. Calls the contract's finalization function.
*/
function finalize() public {
require(!_finalized);
require(hasClosed());

_finalized = true;

_finalization();
emit CrowdsaleFinalized();
}

/**
* @dev Can be overridden to add finalization logic. The overriding function
* should call super._finalization() to ensure the chain of finalization is
* executed entirely.
*/
function _finalization() internal {
}
}