Beanswrapper - java.beans.IntrospectionException: type mismatch between read and write methods

Hello,

We are using beanswrapper here, and every once in a while (this is very hard to reproduce) I see this stack trace:

java.beans.IntrospectionException: type mismatch between read and write methods
at java.beans.PropertyDescriptor.findPropertyType(PropertyDescriptor.java:603)
at java.beans.PropertyDescriptor.setWriteMethod(PropertyDescriptor.java:270)
at java.beans.PropertyDescriptor.<init>(PropertyDescriptor.java:117)
at freemarker.ext.beans.BeansWrapper.populateClassMapWithBeanInfo(BeansWrapper.java:1136)
at freemarker.ext.beans.BeansWrapper.populateClassMap(BeansWrapper.java:1027)
at freemarker.ext.beans.BeansWrapper.introspectClassInternal(BeansWrapper.java:965)
at freemarker.ext.beans.BeansWrapper.introspectClass(BeansWrapper.java:938)
at freemarker.ext.beans.BeanModel.<init>(BeanModel.java:139)
at freemarker.ext.beans.StringModel.<init>(StringModel.java:90)
at freemarker.ext.beans.StringModel$1.create(StringModel.java:75)
at freemarker.ext.beans.BeansModelCache.create(BeansModelCache.java:45)
at freemarker.ext.util.ModelCache.getInstance(ModelCache.java:115)
at freemarker.ext.beans.BeansWrapper.wrap(BeansWrapper.java:463)
....

So after some google searches I've found that this is a problem with a getter/setter not having the same return/first param types.  I've looked through every bean, and unless I'm missing something, the getters & setters all match up.  We do not provide setter methods for read only or calculated properties.

This is the block in beanswrapper that is throwing the error

Method readMethod = pd.getReadMethod();
                    Method publicReadMethod = getAccessibleMethod(readMethod, accessibleMethods);
                    if(publicReadMethod != null && isSafeMethod(publicReadMethod)) {
                        try {
                            if(readMethod != publicReadMethod) {
                                pd = new PropertyDescriptor(pd.getName(),
                                        publicReadMethod, pd.getWriteMethod());
                                pd.setReadMethod(publicReadMethod);
                            }
                            classMap.put(pd.getName(), pd);
                        }
                        catch(IntrospectionException e)
                        {
                            logger.warn("Couldn't properly perform introspection", e);
                        }
                    }


First, can anyone explain why this is happening very rarely?  If it's a getter/setter mismatch, shouldn't it be happening quite often (static code..)?  We've been working on this app since mid August and this has showed itself probably less than 10 times, 2 of which were at the beginning of a demo :-| .  It seems to happen early on after the container is started but not always...

More importantly, since the exception is just swallowed here and nothing is actually thrown, is this exception really exceptional?  Are you logging it to tell me that there is a slight problem I should fix (but it's really no big deal, totally recoverable)?   If so the NAME and containing class of the property that mismatches should be logged (really the java.beans pkg should do this for beans wrapper, but it doesn't..)  Or if it's just noise the log stmt should be removed.   If it's actually a problem, it should be wrapped and thrown, again with the name of the failing property logged.

So if anybody has any tips for how I can find out what property is mismatching and why it is only mismatching under hard to produce user input, please share.  I think I'll have to check out FM and hack this method a bit.  But if a dev could provide some insight on what is happening here and why the catch block does what it does I would really appreciate it.

Thanks,
John

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