docs: public Script getScriptSig() throws ScriptException {
          // Transactions that generate new coins don't actually have a script. Instead this
          // parameter is overloaded to be something totally different.
          Script script = scriptSig == null ? null : scriptSig.get();
          if (script == null) {
              script = new Script(scriptBytes);
              scriptSig = new WeakReference<>(script);
          }
          return script;
      }