Most parts are erased, the method descriptor, the bytecode but the generic signature is kept for enabling separated compilation (you can also retrieve it by ref

Most parts are erased, the method descriptor, the bytecode but the generic signature is kept for enabling separated compilation (you can also retrieve it by reflection). Here the generic signature which is a String is just too big, the dictionary part of the classfile, the constant pool, stores a String as an UTF8 byte array prefixed by its size on 16bits (hence the 65535 limit).