A singleton EJB has @Lock(LockType.READ) annotation declared on the class level.
The bean is accessed using a local (defined by @Local annotation) or remote (defined by @Remote annotation) EJB interface.
SingletonComponent::getLockType returns wrong value (LockType.WRITE) because the beanLevelLockType map does not contain a key equal to the local or remote interface class name. It contains a key equal to the EJB class name that implements those interfaces.