Problem

When an issue has an cascading select field with any value, it will break the JSON export.

• If there is no field value, the JSON export will work fine.

Steps to Reproduce

1. Enable JSON export as detailed here: https://confluence.atlassian.com/display/JIRAKB/How+To+Enable+JSON+Export+in+JIRA
   • Note that this functionality is still in beta
2. Create a cascading select field
3. Configure the options to add a value (like "abc")
4. Create a ticket and populate the cascade field with the "abc" value
5. Attempt to do a JSON export on the issue
6. Note that it fails with a 500 error
7. Perform a JQL search, ensure to include the ticket with a cascading select field
8. Attempt to export the search to JSON
9. Note that the export stops with truncated result set.

Expected Results

The JSON exports would complete

Actual Results

• JQL JSON export data is truncated and stops upon running into the 500 error
• Issue JSON export fails with 500 error
• Error in logs:

  2017-03-07 22:26:16,052 http-nio-8080-exec-3 ERROR      [o.a.c.c.C.[.[localhost].[/].[searchrequest-view]] Servlet.service() for servlet [searchrequest-view] in context with path [] threw exception
  java.lang.RuntimeException: org.codehaus.jackson.JsonGenerationException: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?)
          at com.atlassian.jira.plugins.importer.views.SearchRequestJsonView.writeSearchResults(SearchRequestJsonView.java:67)
          at com.atlassian.jira.plugin.searchrequestview.DefaultSearchRequestURLHandler.handleRequest(DefaultSearchRequestURLHandler.java:372)
          at com.atlassian.jira.web.servlet.SearchRequestViewServlet.doGet(SearchRequestViewServlet.java:25)
          at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
          at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
          ...
  Caused by: org.codehaus.jackson.JsonGenerationException: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?)
          at org.codehaus.jackson.map.ser.impl.FailingSerializer.serialize(FailingSerializer.java:34)
          at org.codehaus.jackson.map.ser.std.MapSerializer.serializeFields(MapSerializer.java:237)
          at org.codehaus.jackson.map.ser.std.MapSerializer.serialize(MapSerializer.java:186)
          at org.codehaus.jackson.map.ser.std.MapSerializer.serialize(MapSerializer.java:23)
          at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:446)
          at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFieldsFiltered(BeanSerializerBase.java:203)
          at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:110)
  		...
  

Workaround

• Remove the cascading select field values from the tickets.