in src/main/java/com/amazonaws/secretsmanager/caching/SecretCache.java [121:126]
public String getSecretString(final String secretId) {
SecretCacheItem secret = this.getCachedSecret(secretId);
GetSecretValueResult gsv = secret.getSecretValue();
if (null == gsv) { return null; }
return gsv.getSecretString();
}