code: public static InsnList loadStringConst(String s) {
          Validate.notNull(s);
          InsnList ret = new InsnList();
          ret.add(new LdcInsnNode(s));
          return ret;
      }
docs: Generates instruction to push a string constant on to the stack.
  @param s string constant to push
  @return instructions to push a string constant
  @throws NullPointerException if any argument is {@code null}