title: SaxParseException content of element include must match EMPTY
body: <p>Executing Mybatis 3.2.8 I am using the element "property" as content for element "include", as stated in the documentation:</p>
  
  <p><a href="http://mybatis.org/mybatis-3/es/sqlmap-xml.html" rel="nofollow" title="MyBatis documentation">http://mybatis.org/mybatis-3/es/sqlmap-xml.html</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;select id="selectUsers" resultType="map"&gt;
    select
      &lt;include refid="userColumns"&gt;&lt;property name="alias" value="t1"/&gt;&lt;/include&gt;,
      &lt;include refid="userColumns"&gt;&lt;property name="alias" value="t2"/&gt;&lt;/include&gt;
    from some_table t1
      cross join some_table t2
  &lt;/select&gt;</code></pre>
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  <p>When I try to execute the above code I get the error: SaxParseException content of element include must match EMPTY</p>
  
  <p>I downloaded the <a href="http://mybatis.org/dtd/mybatis-3-mapper.dtd" rel="nofollow" title="DTD">DTD</a> and it is correct:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!-- Dynamic --&gt;
  
  &lt;!ELEMENT include (property+)?&gt;
  &lt;!ATTLIST include
  refid CDATA #REQUIRED
  &gt;</code></pre>
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  <p>So, why am I getting the Exception?</p>