com.atlassian.jira.issue
Interfaces 
ActionManager
AssignIssueUtils
AttachmentManager
CustomFieldManager
IssueFilter
IssueManager
IssueRelationConstants
Classes 
ActionConstants
AssignIssueUtilsImpl
IssueFieldConstants
IssueFieldUpdateException
IssueUtils
Exceptions 
NoDefaultAssigneeEnterpriseException
NoDefaultAssigneeProfessionalException
SeparatorSelectedException