docs: public void add(final AbstractInsnNode insn) {
          ++size;
          if (last == null) {
              first = insn;
              last = insn;
          } else {
              last.next = insn;
              insn.prev = last;
          }
          last = insn;
          cache = null;
          insn.index = 0; // insn now belongs to an InsnList
      }