When attempting to perform an Bugzilla import for 3.1, the system crashes with Form errors while on the very first issue for the step:
Importing Issues from project(s) 'MyProject'

The same Bugzilla Import works with 3.0.3 and my custom BugzillaImportBean.java based off that version.

Form Errors:

• Error importing data from bugzilla: java.lang.RuntimeException: class com.atlassian.jira.issue.customfields.impl.ReadOnlyCFType passed an invalid value of type: class java.lang.Double at com.atlassian.jira.issue.customfields.impl.AbstractCustomFieldType.assertObjectImplementsType(AbstractCustomFieldType.java:52) at com.atlassian.jira.issue.customfields.impl.TextCFType.getStringFromSingularObject(TextCFType.java:22) at com.atlassian.jira.issue.customfields.impl.StringCFType.getDbValueFromObject(StringCFType.java:15) at com.atlassian.jira.issue.customfields.impl.AbstractSingleFieldType.createValue(AbstractSingleFieldType.java:115) at com.atlassian.jira.issue.fields.CustomFieldImpl.createValue(CustomFieldImpl.java:478) at com.atlassian.jira.util.BugzillaImportBean.createIssue(BugzillaImportBean.java:306) at com.atlassian.jira.util.BugzillaImportBean.createIssues(BugzillaImportBean.java:244) at com.atlassian.jira.util.BugzillaImportBean.create(BugzillaImportBean.java:169) at com.atlassian.jira.web.action.util.BugzillaImport.doRun(BugzillaImport.java:140) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:324) at webwork.util.InjectionUtils$DefaultInjectionImpl.invoke(InjectionUtils.java:61) at webwork.util.InjectionUtils.invoke(InjectionUtils.java:52) at webwork.action.ActionSupport.invokeCommand(ActionSupport.java:417) at webwork.action.ActionSupport.execute(ActionSupport.java:146) at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:46) at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:131) at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service(JiraServletDispatcher.java:186) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:142) at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:58) at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:168) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:177) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132) at com.atlassian.jira.web.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:25) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.jira.web.filters.ActionCleanupDelayFilter.doFilter(ActionCleanupDelayFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:91) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.jira.web.filters.gzip.GzipFilter.doFilter(GzipFilter.java:72) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549) at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666) at java.lang.Thread.run(Thread.java:534)