public int getNumberOfClasses() {
		return number_of_classes & 0xffff;
	}
The value of the {@code number_of_classes} item indicates the number of entries in
the {@code classes} array.
@return {@code number_of_classes}
Ghidra/Processors/JVM/src/main/java/ghidra/javaclass/format/attributes/NestMembersAttribute.java