Is there a way to load data into Selection list UDF field using TCC

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I created a Selection list UDF field, i need to load 100 employee names in this selection field, is there a way to do that using TCC. I created an import script but it is keep giving me following error message, not sure what needs to be setup: any help please?

BaseEntity.getEntityKey(): All fields part of the key need to be initialized before calling getEntityKey().;