JNI java to c bundle

bundle_transactions_t *bundleFromJavaBundle(JNIEnv *env, jobject javaBundle){
    bundle_transactions_t *bundle = NULL;

    bundle_transactions_new(&bundle);

    jclass bundleClass = (*env)->FindClass(env, "org/iota/jota/model/Bundle" );
    jclass transactionClass = (*env)->FindClass(env, "org/iota/jota/model/Transaction" );
    jmethodID getTransactions = (*env)->GetMethodID(env, bundleClass , "getTransactions", "()Ljava/util/List;" );
    jmethodID toTrytes = (*env)->GetMethodID(env, transactionClass , "toTrytes", "()java/lang/String;" );

    jobject txList = (*env)->CallObjectMethod(env, javaBundle, getTransactions );

    jclass listClass = (*env)->FindClass(env, "java/util/List" );
    jmethodID getMethodID = (*env)->GetMethodID(env, listClass, "get", "(I)Ljava/lang/Object;" );
    jmethodID sizeMethodID = (*env)->GetMethodID(env, listClass, "size", "()I" );
    int listItemsCount = (int)(*env)->CallIntMethod(env, txList, sizeMethodID );
    for( int i=0; i<listItemsCount; ++i ){
        jobject javaTx = (*env)->CallObjectMethod(env, txList, getMethodID, i - 1 );
        jstring txTrytes = (*env)->CallObjectMethod(env, javaTx, toTrytes);

        jboolean tx_isCopy;
        tryte_t *c_tx_trytes = (tryte_t *) (*env)->GetStringUTFChars(env, txTrytes, &tx_isCopy);
        size_t trytes_len = strlen(c_tx_trytes);

        flex_trit_t *flex_trits = malloc(numOfFlexTritsForTxTrits * sizeof(flex_trit_t));

        flex_trits_from_trytes(flex_trits, numOfFlexTritsForTxTrits, c_tx_trytes, trytes_len, trytes_len);

        iota_transaction_t *c_transaction = transaction_deserialize(flex_trits, false);
        bundle_transactions_add(bundle, c_transaction);

        if (tx_isCopy == JNI_TRUE) {
            (*env)->ReleaseStringUTFChars(env, c_tx_trytes, txTrytes);
        }
    }

    return bundle;
}