When a COBOL copybook defines a hierarchical group item with multiple nested levels, how does wca4z represent it in Java?

Think of it like working hands-on with IBM mainframe systems — the answer here is 'As a flat Java class with all fields promoted to the top level, ignoring group structure'. wca4z represents COBOL group item hierarchies as nested Java classes, preserving the structural relationship between parent group items and their subordinate data items so the data contract remains fa. On real mainframe exams, this concept comes up repeatedly so make sure you have it locked in.