In a RAP business object, where is the validation implementation code contained?

Comprehensive and Detailed Explanation from Exact Extract:

In RAP, validations, determinations, and actions are implemented inside the local handler class (lhc_...) of the behavior pool.

Global classes are not used directly for RAP BO logic, only for reusable utilities.

Functions or subroutines are not cloud-compliant for RAP implementation.

Thus, validation code always resides in the local handler class inside the RAP behavior pool.

Study Guide Reference: RAP Development Guide – Validations in Behavior Implementation.