Protobuf definition for a tree

message Tree {

    enum TreeType {
    LOG = 1;
    MAP = 2;
    }

    enum HashFunction {
        md5 = 1;  
        sha = 2;
        sha224 = 3;
        sha256 = 4;
        sha384 = 5;
        sha512 = 6;
    }

    required bytes treeId = 1;
    required TreeType treeType = 2;
    required HashFunction hashFunction = 3;
    required bytes root = 4;
    required int64 size = 5;
    map<string,string> backend = 6;
    optional string treeName = 7;
}