Hot Folder Session is null

In my custom Hot Folder task class I need to include certain pre-processing logic that requires usage of model service (and getting some data from flexible search). However, I got the following error:

java.lang.NullPointerException at de.hybris.platform.servicelayer.session.impl.DefaultSessionService.getOrBindSession(DefaultSessionService.java:192)

How can I create a valid session?