Oracle Message ORA-04096 - trigger string has a WHEN clause which is too large, limit 2K

ERRORtrigger string has a WHEN clause which is too large, limit 2K
CAUSEA triggers when clause is limited to 2K for dictionary storage reasons. The trigger being created exceeded that size.
ACTIONUse a smaller when clause. Note, the trigger body could be used to perform the same limiting action as the when clause.