Overview Java 17 includes several platform changes that can break existing code during migration. This article covers four JEPs that affect compatibility: JEP Change Impact 403 Strongly Encapsulate JDK Internals HIGH — breaks libraries using internal APIs 407 Remove RMI Activation LOW — niche feature, deprecated since Java 15 411 Deprecate Security Manager MEDIUM — some applications use SecurityManager 306 Restore Always-Strict Floating-Point LOW — affects numeric edge cases JEP 403: Strongly Encapsulate JDK Internals What Changed In Java 8 and earlier, code could access any JDK internal API via reflection — setAccessible(true) bypassed access controls.