Start of JIRA is blocked due to unavailable dependencies for ExtendedWorklogCustomfield.
Root cause : Some plugin (Gantt plugin, JaM from Go2Group) access to CustomfieldManager before the end of JIRA Start.
It causes a load of all customfield provided by plugin.
If these customfields have direct dependencies (in constructor) on components provided by plugin, they can fail if these components are not yet referenced by Picocontainer.

Resolution :
Avoid direct dependencies, and prefer dependencies only when needed.