We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
CKV_AWS_157 False Positive on Aurora
**Describe the issue**
CKV_AWS_157 fails on Aurora instances even though the `MultiAZ` property is not applicable to Aurora

**Examples**
```
RDSinstance:
    Type: AWS::RDS::DBInstance
    Properties:
      DBClusterIdentifier: !Ref DBCluster
      DBInstanceClass: !Ref DbType
      DBInstanceIdentifier: !Sub ${AppName}-${EnvironmentName}
      DBParameterGroupName: !Ref DbParameterGroup
      DBSubnetGroupName: !Ref DBSubnetGroup
      Engine: aurora-mysql
      MonitoringInterval: "60"
      MonitoringRoleArn: !GetAtt RdsMonitoringRole.Arn
      PubliclyAccessible: 'false'
```

**Version (please complete the following information):**
 - Checkov Version 2.2.270

**Additional context**
- AWS docs: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz

<img width="1377" alt="Screenshot 2023-01-19 at 1 25 49 PM" src="https://user-images.githubusercontent.com/1328683/213552592-4736b84a-3926-44b2-9dad-196b68f28daa.png">


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py`
Content:
```
1 from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck
2 from checkov.common.models.enums import CheckCategories
3 
4 
5 class RDSMultiAZEnabled(BaseResourceValueCheck):
6     def __init__(self):
7         name = "Ensure that RDS instances have Multi-AZ enabled"
8         id = "CKV_AWS_157"
9         supported_resources = ['AWS::RDS::DBInstance']
10         categories = [CheckCategories.NETWORKING]
11         super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)
12 
13     def get_inspected_key(self):
14         return 'Properties/MultiAZ'
15 
16 
17 check = RDSMultiAZEnabled()
18
```
--- 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()

```

diff --git a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py
--- a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py
+++ b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py
@@ -1,5 +1,5 @@
+from checkov.common.models.enums import CheckResult, CheckCategories
 from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck
-from checkov.common.models.enums import CheckCategories
 
 
 class RDSMultiAZEnabled(BaseResourceValueCheck):
@@ -10,6 +10,16 @@
         categories = [CheckCategories.NETWORKING]
         super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)
 
+    def scan_resource_conf(self, conf):
+        # Aurora is replicated across all AZs and doesn't require MultiAZ to be set
+        # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz
+        if 'Properties' in conf.keys():
+            if 'Engine' in conf['Properties'].keys():
+                if 'aurora' in conf['Properties']['Engine']:
+                    return CheckResult.UNKNOWN
+        # Database is not Aurora; Use base class implementation
+        return super().scan_resource_conf(conf)
+            
     def get_inspected_key(self):
         return 'Properties/MultiAZ'

{"golden_diff": "diff --git a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py\n--- a/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py\n+++ b/checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py\n@@ -1,5 +1,5 @@\n+from checkov.common.models.enums import CheckResult, CheckCategories\n from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck\n-from checkov.common.models.enums import CheckCategories\n \n \n class RDSMultiAZEnabled(BaseResourceValueCheck):\n@@ -10,6 +10,16 @@\n         categories = [CheckCategories.NETWORKING]\n         super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)\n \n+    def scan_resource_conf(self, conf):\n+        # Aurora is replicated across all AZs and doesn't require MultiAZ to be set\n+        # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz\n+        if 'Properties' in conf.keys():\n+            if 'Engine' in conf['Properties'].keys():\n+                if 'aurora' in conf['Properties']['Engine']:\n+                    return CheckResult.UNKNOWN\n+        # Database is not Aurora; Use base class implementation\n+        return super().scan_resource_conf(conf)\n+            \n     def get_inspected_key(self):\n         return 'Properties/MultiAZ'\n", "issue": "CKV_AWS_157 False Positive on Aurora\n**Describe the issue**\r\nCKV_AWS_157 fails on Aurora instances even though the `MultiAZ` property is not applicable to Aurora\r\n\r\n**Examples**\r\n```\r\nRDSinstance:\r\n    Type: AWS::RDS::DBInstance\r\n    Properties:\r\n      DBClusterIdentifier: !Ref DBCluster\r\n      DBInstanceClass: !Ref DbType\r\n      DBInstanceIdentifier: !Sub ${AppName}-${EnvironmentName}\r\n      DBParameterGroupName: !Ref DbParameterGroup\r\n      DBSubnetGroupName: !Ref DBSubnetGroup\r\n      Engine: aurora-mysql\r\n      MonitoringInterval: \"60\"\r\n      MonitoringRoleArn: !GetAtt RdsMonitoringRole.Arn\r\n      PubliclyAccessible: 'false'\r\n```\r\n\r\n**Version (please complete the following information):**\r\n - Checkov Version 2.2.270\r\n\r\n**Additional context**\r\n- AWS docs: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz\r\n\r\n<img width=\"1377\" alt=\"Screenshot 2023-01-19 at 1 25 49 PM\" src=\"https://user-images.githubusercontent.com/1328683/213552592-4736b84a-3926-44b2-9dad-196b68f28daa.png\">\r\n\n", "before_files": [{"content": "from checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck\nfrom checkov.common.models.enums import CheckCategories\n\n\nclass RDSMultiAZEnabled(BaseResourceValueCheck):\n    def __init__(self):\n        name = \"Ensure that RDS instances have Multi-AZ enabled\"\n        id = \"CKV_AWS_157\"\n        supported_resources = ['AWS::RDS::DBInstance']\n        categories = [CheckCategories.NETWORKING]\n        super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)\n\n    def get_inspected_key(self):\n        return 'Properties/MultiAZ'\n\n\ncheck = RDSMultiAZEnabled()\n", "path": "checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py"}], "after_files": [{"content": "from checkov.common.models.enums import CheckResult, CheckCategories\nfrom checkov.cloudformation.checks.resource.base_resource_value_check import BaseResourceValueCheck\n\n\nclass RDSMultiAZEnabled(BaseResourceValueCheck):\n    def __init__(self):\n        name = \"Ensure that RDS instances have Multi-AZ enabled\"\n        id = \"CKV_AWS_157\"\n        supported_resources = ['AWS::RDS::DBInstance']\n        categories = [CheckCategories.NETWORKING]\n        super().__init__(name=name, id=id, categories=categories, supported_resources=supported_resources)\n\n    def scan_resource_conf(self, conf):\n        # Aurora is replicated across all AZs and doesn't require MultiAZ to be set\n        # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html#cfn-rds-dbinstance-multiaz\n        if 'Properties' in conf.keys():\n            if 'Engine' in conf['Properties'].keys():\n                if 'aurora' in conf['Properties']['Engine']:\n                    return CheckResult.UNKNOWN\n        # Database is not Aurora; Use base class implementation\n        return super().scan_resource_conf(conf)\n            \n    def get_inspected_key(self):\n        return 'Properties/MultiAZ'\n\n\ncheck = RDSMultiAZEnabled()\n", "path": "checkov/cloudformation/checks/resource/aws/RDSMultiAZEnabled.py"}]}