title: importValue function does not work in cloudformation
body: <p>I see a very strange issue with cloud formation import value function in cloudformation. I am trying to create a cloudformation beanstalk environment. in the configurationTemplate section I have :</p>
  
  <pre><code> configurationTemplateChannel:
  Type: AWS::ElasticBeanstalk::ConfigurationTemplate
  Properties:
    ApplicationName:
    - Fn::ImportValue:
        Fn::Sub: "${StackNamePrefix}-BeanstalkId-test"
    Description: AWS ElasticBeanstalk Sample Configuration Template
    OptionSettings:
         .
         .
         .         
    - Namespace: aws:ec2:vpc
      OptionName: VPCId
      Value:
        Fn::ImportValue:
          Fn::Sub: "${StackNamePrefix}-vpc-VpcId"
       .
       .
       .
  </code></pre>
  
  <p>As you see I have  import in   ApplicationName which result in:</p>
  
  <pre><code>An error occurred (ValidationError) when calling the CreateStack operation: [/Re                    sources/configurationTemplateChannel/Type/OptionSettings/6/Value/0/Fn::ImportVal                    ue] 'null' values are not allowed in templates
  </code></pre>
  
  <p>Am I doing anything wrong? Does this mean that I cannot use import option here?</p>
  
  <p>Any help would be appreciated</p>