https://docs.atlassian.com/software/jira/docs/api/6.2-ClusteringEAP01/com/atlassian/jira/charts/ChartFactory.html
ChartFactory (Atlassian JIRA 6.2-ClusteringEAP01 API)
atlassian jiraapi
https://docs.atlassian.com/software/jira/docs/api/7.0.5/com/atlassian/jira/charts/ChartFactory.PeriodName.html
ChartFactory.PeriodName (Atlassian JIRA 7.0.5 API)
atlassian jiraapi
https://docs.atlassian.com/software/jira/docs/api/7.5.0/com/atlassian/jira/charts/ChartFactory.ChartContext.html
ChartFactory.ChartContext (Atlassian JIRA 7.5.0 API)
atlassian jiraapi