Issue linking is another important feature in JIRA. It helps us to define the relationship between issues. In this recipe, we will see how to create links between issues and to break them using the JIRA APIs.
Before we start, an issue link type has an inward and an outward description. For every issue link, there will be a source issue and a destination issue. From a source issue, we can look up the destination issues by looking up the outward links. Similarly, from a destination issue, we can look up the source issues by looking up inward links.
Make sure the Issue Linking feature is turned ON in JIRA and valid link types are created. This can be done from Administration | System | Issue Features | Issue Linking, as explained at http://confluence.atlassian.com/display/JIRA/Configuring+Issue+Linking.