void readInnerClasses(Class cls) throws IOException {
int nc = readUnsignedShort();
ArrayList<InnerClass> ics = new ArrayList<>(nc);
for (int i = 0; i < nc; i++) {
InnerClass ic =
new InnerClass(readClassRef(),
readClassRefOrNull(),
(Utf8Entry)readRefOrNull(CONSTANT_Utf8),
readUnsignedShort());
ics.add(ic);
}