Migrate data to custom entities

I am trying to find an example of how to import data from csv to custom entities. To regular nodes it works fine, but whe I try to do the same thing for custom entities it fails with

exception ‘DrupalCoreConfigUnmetDependenciesException’ with message ‘Configuration objects (dbl_migration_lhd_boenheter) provided by dbl_migrate have unmet dependencies’

without specifying what those dependencies are. Do you need to make any special process or destination definitions for fields in custom entities?
Anyone got a working example for Migrating data into a custom entity? Have searched but could not find..

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