use normal getter for chain tree

Author: perekopskiy

l1-contracts/contracts/core/message-root/MessageRootBase.sol

@@ -58,7 +58,7 @@ abstract contract MessageRootBase is IMessageRootBase, ReentrancyGuard, Initiali
     /// @dev The incremental merkle tree storing the chain message roots.
     /// @dev On L1, these are empty leaves and are populated only during the addition of the chain
     /// are not updated thereafter.
-    mapping(uint256 chainId => DynamicIncrementalMerkle.Bytes32PushTree tree) public chainTree;
+    mapping(uint256 chainId => DynamicIncrementalMerkle.Bytes32PushTree tree) internal chainTree;
 
     /// @notice The mapping from block number to the global message root.
     /// @dev Each block might have multiple txs that change the historical root. You can safely use the final root in the block,
@@ -341,4 +341,8 @@ abstract contract MessageRootBase is IMessageRootBase, ReentrancyGuard, Initiali
         uint256 index = chainIndex[_chainId];
         return sharedTree.merklePath(index);
     }
+
+    function getChainTree(uint256 chainId) external view returns (DynamicIncrementalMerkle.Bytes32PushTree memory) {
+        return chainTree[chainId];
+    }
 }

l1-contracts/zkstack-out/MessageRootBase.sol/MessageRootBase.json

@@ -173,25 +173,6 @@
     ],
     "stateMutability": "view"
   },
-  {
-    "type": "function",
-    "name": "chainTree",
-    "inputs": [
-      {
-        "name": "chainId",
-        "type": "uint256",
-        "internalType": "uint256"
-      }
-    ],
-    "outputs": [
-      {
-        "name": "_nextLeafIndex",
-        "type": "uint256",
-        "internalType": "uint256"
-      }
-    ],
-    "stateMutability": "view"
-  },
   {
     "type": "function",
     "name": "currentChainBatchNumber",
@@ -243,6 +224,42 @@
     ],
     "stateMutability": "view"
   },
+  {
+    "type": "function",
+    "name": "getChainTree",
+    "inputs": [
+      {
+        "name": "chainId",
+        "type": "uint256",
+        "internalType": "uint256"
+      }
+    ],
+    "outputs": [
+      {
+        "name": "",
+        "type": "tuple",
+        "internalType": "struct DynamicIncrementalMerkle.Bytes32PushTree",
+        "components": [
+          {
+            "name": "_nextLeafIndex",
+            "type": "uint256",
+            "internalType": "uint256"
+          },
+          {
+            "name": "_sides",
+            "type": "bytes32[]",
+            "internalType": "bytes32[]"
+          },
+          {
+            "name": "_zeros",
+            "type": "bytes32[]",
+            "internalType": "bytes32[]"
+          }
+        ]
+      }
+    ],
+    "stateMutability": "view"
+  },
   {
     "type": "function",
     "name": "getMerklePathForChain",