Exception in thread "Thread-6" Exception in thread "main" Exception in thread "Thread-5"

[dpacanins]

Buenas noches

estoy implementando la API para generar CFDIv33 y al momento de sellar me manda el siguiente error:

Exception in thread "Thread-6" Exception in thread "main" Exception in thread "Thread-5"
Exception: java.lang.OutOfMemoryError thrown from the UncaughtExceptionHandler in thread "Thread-6"

el codigo que estoy usando es:

            PrivateKey key = KeyLoaderFactory.createInstance(KeyLoaderEnumeration.PRIVATE_KEY_LOADER, processData.getKeyFIS(), processData.getPwd()).getKey();
            X509Certificate cert = KeyLoaderFactory.createInstance(KeyLoaderEnumeration.PUBLIC_KEY_LOADER, processData.getCertFIS()).getKey();

            cfd.sellar(key, cert);
            cfd.validar();
            cfd.verificar();

alguien podria ayudarme

saludos