Natspec: Inflated feeGrowthGlobal (#366)

* natspec around inflated fee growth global

* updated note

* lint

Author: saucepoint

src/interfaces/ISubscriber.sol

@@ -6,14 +6,17 @@ import {PositionInfo} from "../libraries/PositionInfoLibrary.sol";
 
 /// @notice Interface that a Subscriber contract should implement to receive updates from the v4 position manager
 interface ISubscriber {
+    /// @notice Called when a position subscribes to this subscriber contract
     /// @param tokenId the token ID of the position
     /// @param data additional data passed in by the caller
     function notifySubscribe(uint256 tokenId, bytes memory data) external;
+
     /// @notice Called when a position unsubscribes from the subscriber
     /// @dev This call's gas is capped at `unsubscribeGasLimit` (set at deployment)
     /// @dev Because of EIP-150, solidity may only allocate 63/64 of gasleft()
     /// @param tokenId the token ID of the position
     function notifyUnsubscribe(uint256 tokenId) external;
+
     /// @notice Called when a position is burned
     /// @param tokenId the token ID of the position
     /// @param owner the current owner of the tokenId
@@ -22,8 +25,13 @@ interface ISubscriber {
     /// @param feesAccrued the fees accrued by the position if liquidity was decreased
     function notifyBurn(uint256 tokenId, address owner, PositionInfo info, uint256 liquidity, BalanceDelta feesAccrued)
         external;
+
+    /// @notice Called when a position modifies its liquidity or collects fees
     /// @param tokenId the token ID of the position
     /// @param liquidityChange the change in liquidity on the underlying position
     /// @param feesAccrued the fees to be collected from the position as a result of the modifyLiquidity call
+    /// @dev Note that feesAccrued can be artificially inflated by a malicious user
+    /// Pools with a single liquidity position can inflate feeGrowthGlobal (and consequently feesAccrued) by donating to themselves;
+    /// atomically donating and collecting fees within the same unlockCallback may further inflate feeGrowthGlobal/feesAccrued
     function notifyModifyLiquidity(uint256 tokenId, int256 liquidityChange, BalanceDelta feesAccrued) external;
 }