I am using jira-ext plugin to update issues in jira. When there is a build failure i need to update the issue type as bug.

Following configuration was given:
Update a field

JIRA Field ID   : issuetype

Value                 : name: Bug

The error message that I get is:
Caused by: net.rcarz.jiraclient.RestException: 400 : {"errorMessages":[],"errors":{"issuetype":"Can not instantiate value of type [simple type, class com.atlassian.jira.rest.api.issue.ResourceRef] from JSON String; no single-String constructor/factory method"}}
at net.rcarz.jiraclient.RestClient.request(RestClient.java:160)
at net.rcarz.jiraclient.RestClient.request(RestClient.java:182)
at net.rcarz.jiraclient.RestClient.request(RestClient.java:200)
at net.rcarz.jiraclient.RestClient.put(RestClient.java:380)
at net.rcarz.jiraclient.RestClient.put(RestClient.java:398)
at net.rcarz.jiraclient.Issue$FluentUpdate.execute(Issue.java:189)

Kindly help in resolving this issue ASAP