title: org.apache.axis2.AxisFault: Unknow type can not serialize while passing array of objects in webservice
body: <p>I have created a webservice which takes a DTO as a parameter. And DTO contains an array of objects.
  I've generated WSDL and skeletons and clients. 
  I am trying to invoke the webservice if I pass array of Strings say : 
  Serializable[] array = new String[] { "a", "n" }; it works fine.</p>
  
  <p>Now my requirement is to pass array of HashMaps I am not able to do so, even though HashMap implements Serializable.</p>
  
  <pre><code> HashMap&lt;String, String&gt; hashMap1 = new HashMap&lt;String, String&gt;();
              HashMap&lt;String, String&gt; hashMap2 = new HashMap&lt;String, String&gt;();
              hashMap1.put("key1", "value1");
              hashMap2.put("key1", "value1");
              Serializable[] maps = new HashMap[] { hashMap1, hashMap2 };
              myDTO.setParams(maps);
  
              request.setDTO(myDTO);
              InvokeServiceResponse response = stub.serviceMethod(request);
  </code></pre>
  
  <p>I am using Axis2. 2.1.5, Tomcat 6, and Eclipse Helios.</p>
  
  <p>Stack trace I am pasting here for reference. </p>
  
  <pre><code>org.apache.axis2.AxisFault: Unknow type can not serialize
      at org.apache.axis2.AxisFault.makeFault(AxisFault.java:430)
      at org.apache.axis2.transport.http.SOAPMessageFormatter.writeTo(SOAPMessageFormatter.java:83)
      at org.apache.axis2.transport.http.AxisRequestEntity.writeRequest(AxisRequestEntity.java:84)
      at org.apache.commons.httpclient.methods.EntityEnclosingMethod.writeRequestBody(EntityEnclosingMethod.java:499)
      at org.apache.commons.httpclient.HttpMethodBase.writeRequest(HttpMethodBase.java:2114)
      at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:1096)
      at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:398)
      at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
      at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
      at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:346)
      at org.apache.axis2.transport.http.AbstractHTTPSender.executeMethod(AbstractHTTPSender.java:557)
      at org.apache.axis2.transport.http.HTTPSender.sendViaPost(HTTPSender.java:199)
  </code></pre>