Spring #ConfigurationProperties instance to JSON with jackson: No serializer found - json

Question

I'm having the following code:
#Data
#Validated
#ConfigurationProperties
public class Keys {
private final Key key = new Key();
#Data
#Validated
#ConfigurationProperties(prefix = "key")
public class Key {
private final Client client = new Client();
private final IntentToken intentToken = new IntentToken();
private final Intent intent = new Intent();
private final OAuth oauth = new OAuth();
private final ResourceToken resourceToken = new ResourceToken();
#Valid #NotNull private String authorization;
#Valid #NotNull private String bearer;
...
}
}
That is an instance representing a properties file such as:
key.authorization=Authorization
key.bearer=Bearer
..
As I can have different sources for the properties (properties file, MongoDB, etc), I have a client that inherit from Keys as follow:
Properties files source
#Component
#Configuration
#Primary
#PropertySource("classpath:${product}-keys.${env}.properties")
//#JsonAutoDetect(fieldVisibility = Visibility.ANY)
public class CustomerKeysProperties extends Keys {
}
Mongo source
#Data
#EqualsAndHashCode(callSuper=true)
#Component
//#Primary
#Document(collection = "customerKeys")
public class CustomerKeysMongo extends Keys {
#Id
private String id;
}
I just select the source I want to use annotating the class with #Primary. In the example above, CustomerKeysProperties is the active source.
All this work fine.
The issue I have is when I try to convert an instance of CustomerKeysProperties into JSON, as in the code below:
#SpringBootApplication
public class ConverterUtil {
public static void main(String[] args) throws Exception {
SpringApplication.run(ConverterUtil.class, args);
}
#Component
class CustomerInitializer implements CommandLineRunner {
#Autowired
private Keys k;
private final ObjectMapper mapper = new ObjectMapper();
#Override
public void run(String... args) throws Exception {
mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
//mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
String jsonInString = mapper.writeValueAsString(k);
System.out.println(jsonInString);
}
}
}
While k contains all the properties set, the conversion fails:
Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: x.client.customer.properties.CustomerKeysProperties$$EnhancerBySpringCGLIB$$eda308bd["CGLIB$CALLBACK_0"]->org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor["advised"]->org.springframework.aop.framework.ProxyFactory["targetSource"]->org.springframework.aop.target.SingletonTargetSource["target"]->x.client.customer.properties.CustomerKeysProperties$$EnhancerBySpringCGLIB$$4fd6c568["CGLIB$CALLBACK_0"])
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77)
at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1191)
And if I uncomment
mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false)
as suggested in the logs, I have an infinite loop happening in Jackson causing a stackoverflow:
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727)
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119)
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79)
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18)
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727)
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
..
Questions
At the end, I just want to provide an Util class than can convert a properties file in a JSON format that will be stored in MongoDB.
How can I solve this problem ?
Without passing through the object above, how can I transform a properties file into JSON ?
Can I save an arbitrary Java bean in MongoDB, with the conversion to JSON automagically done ?
The answer to any of the 3 questions above would be helpful.
Notes
To be noted that I use lombok. Not sure if this is the problem.
Another guess is that I'm trying to serialize a Spring managed bean and the proxy it involve cause jackson to not be able to do the serialization ? If so, what can be the turn-around ?
Thanks!

Answer 1

So found the problem:
jackson can't process managed bean.
The turn around was
try (InputStream input = getClass().getClassLoader().getResourceAsStream("foo.properties")) {
JavaPropsMapper mapper = new JavaPropsMapper();
Keys keys = mapper.readValue(input, Keys.class);
ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
String res = ow.writeValueAsString(keys);
System.out.println(res);
} catch (IOException e) {
e.printStackTrace();
}
where Keys was the Spring managed bean I was injecting.
And:
JavaPropsMapper come from:
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-properties</artifactId>
</dependency>