We recently migrated our application from spring 3.0.5 to spring 4.1.3 version. In previous version our form rendered without any issues even if we have '[]' (brackets for a map attribute) in the path name. But in spring 4.1.3 we are getting the following exception.

=============================================================

[4/8/15 16:25:30:639 EDT] 0000003c SystemOut O**** start currentCarrier ...23955 _ BCC - obsolete
[4/8/15 16:25:30:657 EDT] 0000003c SystemOut O *** start currentCarrierList ...1
[4/8/15 16:25:30:667 EDT] 0000003c OptionsTag    E org.springframework.web.servlet.tags.RequestContextAwareTag doStartTag null
             java.lang.NullPointerException
at org.springframework.validation.AbstractPropertyBindingResult.findEditor(AbstractPropertyBindingResult.java:160)
at org.springframework.web.servlet.support.BindStatus.findEditor(BindStatus.java:326)
at org.springframework.web.servlet.tags.form.OptionWriter.getDisplayString(OptionWriter.java:246)
at org.springframework.web.servlet.tags.form.OptionWriter.renderOption(OptionWriter.java:223)
at org.springframework.web.servlet.tags.form.OptionWriter.doRenderFromCollection(OptionWriter.java:211)
at org.springframework.web.servlet.tags.form.OptionWriter.renderFromCollection(OptionWriter.java:180)
at org.springframework.web.servlet.tags.form.OptionWriter.writeOptions(OptionWriter.java:133)
at org.springframework.web.servlet.tags.form.OptionsTag.writeTagContent(OptionsTag.java:157)
at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:84)
at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
at com.ibm._jsp._multiple_2D_quote_2D_experience_2D_inputs._jspx_meth_form_options_0(_multiple_2D_quote_2D_experience_2D_inputs.java:1654)
at 
====================================================


    CurrentCarrier.java 
    ===================
    public class CurrentCarrier implements Serializable{
        private String currentCarrier = "";
        private long currentCarrierRefId = 0;
        // and all setter and getter methods
    }

    public class MultipleQuoteInputsForm {
        private Map currentCarrierMap = new HashMap();

        public Object getCurrentCarrierMap(Object key) {
            return currentCarrierMap.get(key);
        }

        public Object setCurrentCarrierMap(Object key, Object value) {
            return currentCarrierMap.put(key, value);
        }

        public Map getCurrentCarrierMap() {
            return currentCarrierMap;
        }
        void setCurrentCarrierMap(Map currentCarrierMap) {
            this.currentCarrierMap = currentCarrierMap;
        }
    }


    MyJsp.jsp:
    =========    
    <form:form action="/saveMultipleQuoteInputs.sp" name="MultipleQuoteInputsForm" commandName="multipleQuoteInputsForm" id="MultipleQuoteInputsForm">
         <form:select path="currentCarrierMap['23456']">  // here the exception becuase of '[]' in path
            <form:options items="${currentCarrierList}" itemLabel="currentCarrier"   itemValue="currentCarrierRefId"/>
        </form:select>
    </form:form>



    MyAction Class :
    ====================
    @RequestMapping(value = "/quote/showMultipleQuoteInputsPage.sp", method = {
            RequestMethod.POST, RequestMethod.GET })
    public ModelAndView execute(
            @ModelAttribute("multipleQuoteInputsForm") MultipleQuoteInputsForm multipleQuoteInputsForm,
            HttpServletRequest request, HttpServletResponse response) {

        multipleQuoteInputsForm.setCurrentCarrierMap("23456", "9999");

        List currentCarrierList = referenceTableService.getCurrentCarrier();
        multipleQuoteInputsForm.setCurrentCarrierList(currentCarrierList);
        return new ModelAndView("/quote/jsp/MyJsp.jsp",
                        Constants.MESSAGE_UTILITY, messageUtility);

    }

I am able to print the ${currentCarrierList} object values using system.out before start of tag.

If i remove '[]' from path the page is rendering, but not selecting the correct select box option.

working but not retaining the selected value
============================================
    <form:select path="currentCarrierMap"> 
        <form:options items="${currentCarrierList}" itemLabel="currentCarrier"   itemValue="currentCarrierRefId"/>
    </form:select>


Not working (because of [] in path). This worked in spring 3.0.5:
=====================================
    <form:select path="currentCarrierMap['23456']">
        <form:options items="${multipleQuoteInputsForm.currentCarrierList}" itemLabel="currentCarrier" itemValue="currentCarrierRefId" />
    </form:select>

When I debug the source code of spring, i see the following difference in BeanWrapper class.

    PropertyTokenHolder tokens = getPropertyNameTokens(finalPath);
    PropertyDescriptor pd = nestedBw.getCachedIntrospectionResults().getPropertyDescriptor(tokens.actualName);
    if (pd != null) {
        if (tokens.keys != null) {
            if (pd.getReadMethod() != null || pd.getWriteMethod() != null) {
                return TypeDescriptor.nested(property(pd), tokens.keys.length);
            }
        }
    }

Don't know how to handle the 'tokens.keys'. I need to have my path in 'xxx[1234]' format. I tried different ways but none of them working.

Please help me. !!!!

Ok. Now I found the solution for this issue. After changing my form attribute to use Generics, solves the issue.

      public class MultipleQuoteInputsForm {
        private Map<String,String> currentCarrierMap = new HashMap<String,String>();

        public Map<String,String> getCurrentCarrierMap(Object key) {
            return currentCarrierMap.get(key);
        }

        public String setCurrentCarrierMap(Object key, Object value) {
            return currentCarrierMap.put(key, value);
        }

        public Map<String,String> getCurrentCarrierMap() {
            return currentCarrierMap;
        }

        void setCurrentCarrierMap(Map<String,String> currentCarrierMap) {
            this.currentCarrierMap = currentCarrierMap;
        }
    }

Now my page is rendering without any issue even if we have '[]' in path attribute.