prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  [Bug] MISSING for Object Conf cls argument
  # 🐛 Bug
  
  OmegaConf cls argument should not be a mandatory value if target is defined. Can we change this to be an optional value with None being the default?
   
  ** Stack trace/error message **
  ```
  omegaconf.errors.MissingMandatoryValue: Missing mandatory value: scheduler.cls
          full_key: scheduler.cls
          reference_type=ObjectConf
          object_type=ObjectConf
  ```
  
  
  ## System information
  - **Hydra Version** :  1.0.0rc2
  - **Python version** : 3.7.7
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `hydra/types.py`
  Content:
  ```
  1 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
  2 from dataclasses import dataclass, field
  3 from enum import Enum
  4 from typing import Any, Callable, Dict
  5 
  6 from omegaconf import MISSING
  7 
  8 TaskFunction = Callable[[Any], Any]
  9 
  10 
  11 @dataclass
  12 # This extends Dict[str, Any] to allow for the deprecated "class" field.
  13 # Once support for class field removed this can stop extending Dict.
  14 class ObjectConf(Dict[str, Any]):
  15     # class, class method or function name
  16     target: str = MISSING
  17 
  18     # parameters to pass to cls when calling it
  19     params: Any = field(default_factory=dict)
  20 
  21     # cls is deprecated, use target, cls will be removed in Hydra 1.1
  22     cls: str = MISSING
  23 
  24     # class is deprecated, use target, class will be removed in Hydra 1.1
  25     # (class is Python keyword and is only supported through DictConfig)
  26     # class: str = MISSING
  27 
  28 
  29 class RunMode(Enum):
  30     RUN = 1
  31     MULTIRUN = 2
  32
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/hydra/types.py b/hydra/types.py
  --- a/hydra/types.py
  +++ b/hydra/types.py
  @@ -18,13 +18,6 @@
       # parameters to pass to cls when calling it
       params: Any = field(default_factory=dict)
   
  -    # cls is deprecated, use target, cls will be removed in Hydra 1.1
  -    cls: str = MISSING
  -
  -    # class is deprecated, use target, class will be removed in Hydra 1.1
  -    # (class is Python keyword and is only supported through DictConfig)
  -    # class: str = MISSING
  -
   
   class RunMode(Enum):
       RUN = 1
  
verification_info: {"golden_diff": "diff --git a/hydra/types.py b/hydra/types.py\n--- a/hydra/types.py\n+++ b/hydra/types.py\n@@ -18,13 +18,6 @@\n     # parameters to pass to cls when calling it\n     params: Any = field(default_factory=dict)\n \n-    # cls is deprecated, use target, cls will be removed in Hydra 1.1\n-    cls: str = MISSING\n-\n-    # class is deprecated, use target, class will be removed in Hydra 1.1\n-    # (class is Python keyword and is only supported through DictConfig)\n-    # class: str = MISSING\n-\n \n class RunMode(Enum):\n     RUN = 1\n", "issue": "[Bug] MISSING for Object Conf cls argument\n# \ud83d\udc1b Bug\r\n\r\nOmegaConf cls argument should not be a mandatory value if target is defined. Can we change this to be an optional value with None being the default?\r\n \r\n** Stack trace/error message **\r\n```\r\nomegaconf.errors.MissingMandatoryValue: Missing mandatory value: scheduler.cls\r\n        full_key: scheduler.cls\r\n        reference_type=ObjectConf\r\n        object_type=ObjectConf\r\n```\r\n\r\n\r\n## System information\r\n- **Hydra Version** :  1.0.0rc2\r\n- **Python version** : 3.7.7\r\n\n", "before_files": [{"content": "# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved\nfrom dataclasses import dataclass, field\nfrom enum import Enum\nfrom typing import Any, Callable, Dict\n\nfrom omegaconf import MISSING\n\nTaskFunction = Callable[[Any], Any]\n\n\n@dataclass\n# This extends Dict[str, Any] to allow for the deprecated \"class\" field.\n# Once support for class field removed this can stop extending Dict.\nclass ObjectConf(Dict[str, Any]):\n    # class, class method or function name\n    target: str = MISSING\n\n    # parameters to pass to cls when calling it\n    params: Any = field(default_factory=dict)\n\n    # cls is deprecated, use target, cls will be removed in Hydra 1.1\n    cls: str = MISSING\n\n    # class is deprecated, use target, class will be removed in Hydra 1.1\n    # (class is Python keyword and is only supported through DictConfig)\n    # class: str = MISSING\n\n\nclass RunMode(Enum):\n    RUN = 1\n    MULTIRUN = 2\n", "path": "hydra/types.py"}], "after_files": [{"content": "# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved\nfrom dataclasses import dataclass, field\nfrom enum import Enum\nfrom typing import Any, Callable, Dict\n\nfrom omegaconf import MISSING\n\nTaskFunction = Callable[[Any], Any]\n\n\n@dataclass\n# This extends Dict[str, Any] to allow for the deprecated \"class\" field.\n# Once support for class field removed this can stop extending Dict.\nclass ObjectConf(Dict[str, Any]):\n    # class, class method or function name\n    target: str = MISSING\n\n    # parameters to pass to cls when calling it\n    params: Any = field(default_factory=dict)\n\n\nclass RunMode(Enum):\n    RUN = 1\n    MULTIRUN = 2\n", "path": "hydra/types.py"}]}