add mass refund method

contracts/common/BiconomySponsorshipPaymasterErrors.sol

@@ -106,4 +106,9 @@ contract BiconomySponsorshipPaymasterErrors {
      * @notice Thrown when trying to directly withdraw instead of submitting a request
      */
     error SubmitRequestInstead();
+
+    /**
+     * @notice Thrown when the array lengths are not equal
+     */
+    error InvalidArrayLengths();
 }

contracts/sponsorship/BiconomySponsorshipPaymaster.sol

@@ -115,6 +115,21 @@ contract BiconomySponsorshipPaymaster is
         emit VerifyingSignerChanged(oldSigner, newVerifyingSigner, msg.sender);
     }
 
+    /**
+     * @dev Refund balances for multiple paymasterIds
+     * PM charges more than it should to protect itself. 
+     * This function is used to refund the extra amount 
+     * when the real consumption is known.
+     * @param paymasterIds The paymasterIds to refund
+     * @param amounts The amounts to refund
+     */
+    function refundBalances(address[] calldata paymasterIds, uint256[] calldata amounts) external payable onlyOwner {
+        if (paymasterIds.length != amounts.length) revert InvalidArrayLengths();
+        for (uint256 i; i < paymasterIds.length; i++) {
+            paymasterIdBalances[paymasterIds[i]] += amounts[i];
+        }
+    }
+
     /**
      * @dev Set a new trusted paymasterId.
      * Can only be called by the owner of the contract.