update mysteryboxV1

contracts/external/ERC721/ERC721.sol

@@ -27,7 +27,7 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
     // Token symbol
     string internal _symbol;
 
-    string internal _baseURI = "";
+    string internal _baseUri = "";
 
     // Mapping from token ID to owner address
     mapping (uint256 => address) private _owners;
@@ -87,12 +87,20 @@ contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
     function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
         require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
 
-        string memory baseURI = _baseURI;
+        string memory baseURI = _baseURI();
         return bytes(baseURI).length > 0
             ? string(abi.encodePacked(baseURI, tokenId.toString()))
             : '';
     }
 
+    /**
+     * @dev Base URI for computing {tokenURI}. Empty by default, can be overriden
+     * in child contracts.
+     */
+    function _baseURI() internal view virtual returns (string memory) {
+        return _baseUri;
+    }
+
     /**
      * @dev See {IERC721-approve}.
      */

contracts/external/ERC721/ERC721URIStorage.sol

@@ -0,0 +1,67 @@
+// This is a file copied from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/extensions/ERC721URIStorage.sol
+// SPDX-License-Identifier: MIT
+
+pragma solidity 0.6.9;
+
+import "./ERC721.sol";
+
+/**
+ * @dev ERC721 token with storage based token URI management.
+ */
+abstract contract ERC721URIStorage is ERC721 {
+    using Strings for uint256;
+
+    // Optional mapping for token URIs
+    mapping (uint256 => string) private _tokenURIs;
+
+    /**
+     * @dev See {IERC721Metadata-tokenURI}.
+     */
+    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
+        require(_exists(tokenId), "ERC721URIStorage: URI query for nonexistent token");
+
+        string memory _tokenURI = _tokenURIs[tokenId];
+        string memory base = _baseURI();
+
+        // If there is no base URI, return the token URI.
+        if (bytes(base).length == 0) {
+            return _tokenURI;
+        }
+        // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
+        if (bytes(_tokenURI).length > 0) {
+            return string(abi.encodePacked(base, _tokenURI));
+        }
+
+        return super.tokenURI(tokenId);
+    }
+
+    /**
+     * @dev Sets `_tokenURI` as the tokenURI of `tokenId`.
+     *
+     * Requirements:
+     *
+     * - `tokenId` must exist.
+     */
+    function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
+        require(_exists(tokenId), "ERC721URIStorage: URI set of nonexistent token");
+        _tokenURIs[tokenId] = _tokenURI;
+    }
+
+    /**
+     * @dev Destroys `tokenId`.
+     * The approval is cleared when the token is burned.
+     *
+     * Requirements:
+     *
+     * - `tokenId` must exist.
+     *
+     * Emits a {Transfer} event.
+     */
+    function _burn(uint256 tokenId) internal virtual override {
+        super._burn(tokenId);
+
+        if (bytes(_tokenURIs[tokenId]).length != 0) {
+            delete _tokenURIs[tokenId];
+        }
+    }
+}

contracts/external/ERC721/InitializableERC721.sol

@@ -14,11 +14,11 @@ contract InitializableERC721 is ERC721 {
         address creator,
         string memory name,
         string memory symbol,
-        string memory baseUrI
+        string memory baseUri
     ) public {
         _name = name;
         _symbol = symbol;
-        _baseURI = baseUrI;
+        _baseUri = baseUri;
         _mint(creator, 0);
     }
 }