How to get the Uri for the aws:lambda function as a text?

I'm trying to link an API Gateway to prefined lambda function. However it says unsupported property Uri. My lambda function is created in the given region as "SayHelloFunction".

  SayHello:
    Type: "AWS::ApiGateway::Method"
    DependsOn:
      - RootApi
      - HelloResource
    Properties:
      RestApiId: !Ref RootApi
      ResourceId: !Ref HelloResource
      HttpMethod: PUT
      MethodResponses:
        - StatusCode: 200
      AuthorizationType: NONE
      ApiKeyRequired: true
      Integration:
        IntegrationHttpMethod: PUT
        IntegrationResponses:
          - StatusCode: 200
        Type: AWS_PROXY
      Uri: 'arn:aws:apigateway:us-east-2:lambda:path/2015-03-31/functions/arn:aws:lambda:us-east-2:xxxxxxxxxxxx:function:SayHelloFunctionFunctionArn/invocations'

Please help.