private int getMinimumPackedStructureLength() {
		if (!isStructureContainer()) {
			throw new IllegalStateException();
		}

		Entry<Integer, CompositeMember> lastEntry = structureMemberOffsetMap.lastEntry();
		if (lastEntry == null) {
			return 0;
		}

		int lastOffset = lastEntry.getKey();
		CompositeMember lastMember = lastEntry.getValue();
		return lastOffset + lastMember.getLength();
	}
Attempt to add a child member to this composite hierarchy
@param child PDB data-type member record
@param monitor task monitor
@return true if child data type resolved and it was successfully added to composite hierarchy,
false if unable to resolve member's data-type or other error occurred.
NOTE: there may be complex hierarchies not yet handled.
@throws CancelledException if operation cancelled
@throws DataTypeDependencyException if child's datatype can not be resolved.
It may be possible to skip and continue with next child.
Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb/DefaultCompositeMember.java