Add rollupManager initializer versioning

contracts/v2/PolygonRollupManager.sol

@@ -270,6 +270,9 @@ contract PolygonRollupManager is
     // Last timestamp when an aggregation happen
     uint64 public lastAggregationTimestamp;
 
+    // Current rollup manager version
+    string public constant ROLLUP_MANAGER_VERSION = "pessimistic";
+
     // Trusted aggregator timeout, if a sequence is not verified in this time frame,
     // everyone can verify that sequence
     /// @custom:oz-renamed-from trustedAggregatorTimeout
@@ -382,6 +385,11 @@ contract PolygonRollupManager is
      */
     event SetBatchFee(uint256 newBatchFee);
 
+    /**
+     * @dev Emitted when rollup manager is upgraded
+     */
+    event UpdateRollupManagerVersion(string rollupManagerVersion);
+
     /**
      * @param _globalExitRootManager Global exit root manager address
      * @param _pol POL token address
@@ -400,6 +408,13 @@ contract PolygonRollupManager is
         _disableInitializers();
     }
 
+    /**
+     * Initializer function to set new rollup manager version
+     */
+    function initialize() external virtual reinitializer(3) {
+        emit UpdateRollupManagerVersion(ROLLUP_MANAGER_VERSION);
+    }
+
     ///////////////////////////////////////
     // Rollups management functions
     ///////////////////////////////////////

test/contractsv2/PolygonRollupManager-Pessimistic.test.ts

@@ -166,6 +166,8 @@ describe("Polygon Rollup Manager with Polygon Pessimistic Consensus", () => {
             emergencyCouncil.address
         );
 
+        await expect(rollupManagerContract.initialize()).to.emit(rollupManagerContract, "UpdateRollupManagerVersion")
+
         // fund sequencer address with Matic tokens
         await polTokenContract.transfer(trustedSequencer.address, ethers.parseEther("1000"));
     });