Orchestrator: System Value "User Name" is sending NULL value

Hello.

We created an Orchestration to update an external database. There is a field to register the user that is doing the update, and I put the "User Name" System Value for it. However, it is sending NULL value, and it causes an exception in AIS server, because the table that will be updated doesn't accept NULL value in that field. The exception is that:

Orchestration Aborted java.lang.Exception: ServiceRequest JDE_SREQ_CONN_SPV_INS_PESSOA: org.codehaus.groovy.runtime.InvokerInvocationException: java.sql.SQLException: ORA-01407: cannot update ("BASETST"."PESSOA"."USUARIO_ULT_ALTERACAO") to NULL

I found that, if we put a default value in "User Name", it works.