Hello!
I have followed instructions and your demo and many other things. I can`t get the excel exporter to work properly, however all the other export methods do. My grid has a filter, when I filter the grid down to one single item, the excel export works. Ive dumbed down my implementation to its simplest form and yet nothing. I get:
Servlet.service() for servlet [springServlet] in context with path [] threw exception [com.vaadin.flow.server.ServiceException: java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because the return value of "java.util.Map$Entry.getValue()" is null] with root cause java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because the return value of "java.util.Map$Entry.getValue()" is null at org.apache.poi.xssf.model.StylesTable.getNumberFormatId(StylesTable.java:302) ~[poi-ooxml-5.2.2.jar:5.2.2]
&
Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'application/octet-stream']
when I click on the excel export button and theres more than one element in my grid.
Please help! This a great new addon and woul really really like to use it! Thank you!