title: MUNIT4 :java.util.LinkedHashMap cannot be cast to org.mule.extension.http.api.HttpRequestAttributes
body: <p>Imtrying munit set-event processor;</p>
  
  <pre><code>&lt;munit:behavior &gt;
              &lt;munit:set-event doc:name="Set Event" doc:id="3ffb4e58-3938-4316-9533-f0031ad492a6" &gt;
                  &lt;munit:payload value='{ .. }' encoding="UTF-8" mediaType="application/json" /&gt;
                  &lt;munit:attributes value="#[{headers:{'application-id':'test'},method:'POST'}]" /&gt;
  
              &lt;/munit:set-event&gt;
  </code></pre>
  
  <p>It reads my payload and attributes coreectly. I put a log and checked. 
  But after that I get;</p>
  
  <pre><code>ERROR 2020-05-21 15:46:23,622 [[MuleRuntime].cpuLight.05: [xxxx-api-v1].raml-main.CPU_LITE @41d3521e] org.mule.runtime.core.internal.exception.OnErrorPropagateHandler: 
  ********************************************************************************
  Message               : java.util.LinkedHashMap cannot be cast to org.mule.extension.http.api.HttpRequestAttributes.
  Element               : raml-main/processors/4 @ xxxxxx-api-v1:api.xml:57
  Element XML           : &lt;apikit:router config-ref="raml-config"&gt;&lt;/apikit:router&gt;
  Error type            : MULE:UNKNOWN
  --------------------------------------------------------------------------------
  Root Exception stack trace:
  java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to org.mule.extension.http.api.HttpRequestAttributes
      at org.mule.module.apikit.Router.processEvent(Router.java:133)
      at org.mule.module.apikit.Router.processWithExtension(Router.java:122)
      at org.mule.runtime.core.privileged.processor.MessageProcessors.lambda$flatMap$13(MessageProcessors.java:338)
  </code></pre>
  
  <p>Why is that? what is wrong in my set-event processor?</p>