jstl 2.0 spring checkboxes checked ternary operator

I work with Spring MVC and jstl 2.0

In a form I have two checkboxes. I want to check only one depends on a variable value.

I have a variable tipoUsuarioTrim that can have two values E and P. If the value is E I want to check a checkbox, if the value is P the another one.

I use the ternary operator.

But in the screen I see the two checkboxes checked.

This is my jsp

    <form:form
    action="${pageContext.request.contextPath}/correos/salvarPaginaCorreos"
    name="frm" id="salvar-pagina-correos"  modelAttribute="listaEncuestados" method="post">
    <c:forEach items="${listaEncuestados.encuestadosErroneos}" var="filaEncuestado" begin="${listaEncuestados.start}"
    end="${listaEncuestados.stop}" varStatus="loop">

            <c:set var="indice" value="${loop.index}" />
           <c:set var="encuestado" value="${listaEncuestados.encuestadosErroneos[loop.index]}" />
            <c:set var="tipoUsuario" value="${encuestado.tipoUsuario}" />
            <c:set var="tipoUsuarioTrim"
                                value="${fn:trim(tipoUsuario)}" />

         <div style="display: inline-block;margin-left:45px;">
        <form:checkbox path="encuestadosErroneos[${loop.index}].tipoUsuario"  class="correo" id="correo"  name="correo"  value="E" onclick="enableDisableCorreo(${loop.index});" 
    ${(tipoUsuarioTrim == 'P' ? "checked='checked'" : ""} 
    />

  </div>
  <div style="display: inline-block;margin-left:50px;">

   <form:checkbox path="encuestadosErroneos[${loop.index}].tipoUsuario"  class="postal" id="postal" name="postal" value="P" onclick="enableDisablePostal(${loop.index});"
   ${(tipoUsuarioTrim == 'E' ? "checked='checked'" : ""} 
    />
   </div>
   </c:forEach>
  </form:form>

This is a form screen

tipoUsuarioTrim has the value E but the two checkboxes are checked

How can I check only one checkbox depends on a variable value?