Springframework.data.domain.page.map SpelEvaluationException "Property of field "timestamp" cannot be found.."

Question

I try to implement pagination support. After successfully getting a Page from the service I want to convert it to objects which have the given Strings as primary keys. After the paging information should remain.

I tried the following:

Page<String> userIds = studentService.getAllUserIds(pageable);
Page<StudentStatistics> studentStatistics = userIds.map(new Converter<String, StudentStatistics>(){
            @Override
            public StudentStatistics convert(String userId) {
                return answerService.getUserStatistics(userId);
            }
        });

Or:

List<StudentStatistics> studentStatistics = new ArrayList<StudentStatistics>();
    for(String userId : userIds){
        studentStatistics.add(answerService.getUserStatistics(userId));
    }
new PageImpl<>(studentStatistics, pageable, userIds.getTotalElements()));

Both ended up in the exception:

org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 0): Property or field 'timestamp' cannot be found on object of type 'java.util.HashMap' - maybe not public?
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:224)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:94)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:81)
    at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:120)
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:242)
    at org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$ExpressionResolver.resolvePlaceholder(ErrorMvcAutoConfiguration.java:279)
    at org.springframework.boot.autoconfigure.web.NonRecursivePropertyPlaceholderHelper$NonRecursivePlaceholderResolver.resolvePlaceholder(NonRecursivePropertyPlaceholderHelper.java:56)
    at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:147)
    at org.springframework.boot.autoconfigure.web.NonRecursivePropertyPlaceholderHelper.parseStringValue(NonRecursivePropertyPlaceholderHelper.java:38)
    at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126)
    at org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$SpelView.render(ErrorMvcAutoConfiguration.java:217)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) 
...

Why does this exception get thrown in this case? Does the Page entity has timestamp properties?

What would be an elegant way to solve this?

Kind regards

---

UPDATE: The spel.SpelEvaluationException error is usually caused when you have an error in the query syntax of the repository module. When you do not use native queries you can face this error using the Spel feature of Springs queries.