Prerequisites for upgrading Java-based Agents not correctly described in documentation, they differ from the System Agents Prerequisites.
Release : 12.3
Component : AUTOMATION ENGINE
Java Agents like SQL or SAP need as prerequisite to be started by a Service Manager 12.3.x so that the CAU works.
Additionally, the phrase "If the agent is not started by a Service Manager, the agent will be ended and the binaries will be upgraded" only applies to System Agents.
CAU for Java-Based Agents only work starting on version 12.3