Error in building a soaprequest

There seems to be a bug in composing a soap request when text in the body containing certain characters. On a request we got back that the message was not wellformed. Looking at the raw request we see a kind of mixing up with two body elements. Deducing we found out it goes wrong when the text contains the following characters "{${". 

When we have a request like this in the xml-view:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:oob="http://www.OOBCWS03.OOBI0103.Request.com">

   <soapenv:Header/>

   <soapenv:Body>

      <oob:OOBCWS03Operation>

         <oob:OOBCWS03Operatie>

            <oob:cgn_tekstuit_indi>xxx</oob:cgn_tekstuit_indi>

            <oob:tekstuiti>{${</oob:tekstuiti>

         </oob:OOBCWS03Operatie>

      </oob:OOBCWS03Operation>

   </soapenv:Body>

</soapenv:Envelope>

We see after the invoke in the raw-view, a kind of mixed up request:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:oob="http://www.OOBCWS03.OOBI0103.Request.com">

   <soapenv:Header/>

   <soapenv:Body>

      <oob:OOBCWS03Operation>

         <oob:OOBCWS03Operatie>

            <oob:cgn_tekstuit_indi>xxx</oob:cgn_tekstuit_indi>

            <oob:tekstuiti>{<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:oob="http://www.OOBCWS03.OOBI0103.Request.com">

   <soapenv:Header/>

   <soapenv:Body>

      <oob:OOBCWS03Operation>

         <oob:OOBCWS03Operatie>

            <oob:cgn_tekstuit_indi>xxx</oob:cgn_tekstuit_indi>

            <oob:tekstuiti>{${</oob:tekstuiti>

         </oob:OOBCWS03Operatie>

      </oob:OOBCWS03Operation>

   </soapenv:Body>

</soapenv:Envelope

As far as we know the characters {$ don't have a special meaning in XML, so it shouldn.t be a problem.

When we have a message with only "{$" (instead of "{${" ) the composing goes well:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:oob="http://www.OOBCWS03.OOBI0103.Request.com">

   <soapenv:Header xmlns:wsa="http://www.w3.org/2005/08/addressing"><wsa:Action>http://www.OOBCWS03.OOBI0103.com/OOBCWS03Port/OOBCWS03OperationRequest</wsa:Action><wsa:MessageID>uuid:25baf000-fc16-4fb5-902a-bcad09970de9</wsa:MessageID><wsa:To>https://APMVST1.BELASTINGDIENST.NL:3304/OOBCWS03</wsa:To></soapenv:Header>

   <soapenv:Body>

      <oob:OOBCWS03Operation>

         <oob:OOBCWS03Operatie>

            <oob:cgn_tekstuit_indi>xxx</oob:cgn_tekstuit_indi>

            <oob:tekstuiti>{$</oob:tekstuiti>

         </oob:OOBCWS03Operatie>

      </oob:OOBCWS03Operation>

   </soapenv:Body>

</soapenv:Envelope>

The soapUI version we are using is 5.4.0. Are we doing something wrong or is this a bug?

Kind regards,

Iwan Mensink