MongoId strings not returning. about ground-db HOT 5 OPEN

MongoID.idStringify = function (id) {                                                                 // 56
  if (id instanceof MongoID.ObjectID) {                                                               // 57
    return id.valueOf();                                                                              // 58
  } else if (typeof id === 'string') {                                                                // 59
    if (id === "") {                                                                                  // 60
      return id;                                                                                      // 61
    } else if (id.substr(0, 1) === "-" || // escape previously dashed strings                         // 62
               id.substr(0, 1) === "~" || // escape escaped numbers, true, false                      // 63
               MongoID._looksLikeObjectID(id) || // escape object-id-form strings                     // 64
               id.substr(0, 1) === '{') { // escape object-form strings, for maybe implementing later
      return "-" + id;                                                                                // 66
    } else {                                                                                          // 67
      return id; // other strings go through unchanged.                                               // 68
    }                                                                                                 // 69
  } else if (id === undefined) {                                                                      // 70
    return '-';                                                                                       // 71
  } else if (typeof id === 'object' && id !== null) {                                                 // 72
    throw new Error("Meteor does not currently support objects other than ObjectID as ids");          // 73
  } else { // Numbers, true, false, null                                                              // 74
    return "~" + JSON.stringify(id);                                                                  // 75
  }                                                                                                   // 76
}; 

new Meteor.Collection.ObjectID()._str

8298e2f637a1a4b9e114abe8