HAProxy sidecars for mTLS. Hystrix for circuit breaking. Apache Camel between layers within the same service. Six API versions. A mandated common framework. A squash merge ban. Each decision was defensible. Combined, they created a system that took three months to onboard into.
SAP Commerce OCC promises a stateless REST API for headless commerce. Underneath, every request hydrates an HTTP session and routes through the same stateful facades built for the JSP storefront. The API is stateless in contract but stateful in implementation.
The SAP Commerce Converter/Populator pattern optimized for extensibility at the cost of predictability. Deep chaining, invisible runtime graphs, and JVM heap exhaustion are the consequences.