`java.util.Optional` deserialisation fails when using `TypeFactory.defaultInstance` for creating `JavaType` for `Optional<?>`

[mattlocker]

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Describe the bug

I am using Camunda 7.21 which uses Jackson. I don't know if it's using jackson the wrong way but still I want to point out a very strange behavior in jackson when deserialising an Optional value.

Version Information

2.x (tested 2.19.x, 2.18.x,2.17.x)

Reproduction

  public static void main(String[] args)
      throws StreamReadException, DatabindException, ClassNotFoundException, IOException {
    ObjectMapper mapper = new ObjectMapper();
    mapper.registerModule(new ParameterNamesModule())
        .registerModule(new Jdk8Module())
        .registerModule(new JavaTimeModule());
    mapper.enable(Feature.ALLOW_UNQUOTED_FIELD_NAMES);
    mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);

    // works as expected
    // prints Optional.empty
    System.out.println(mapper.readValue(mapper.treeAsTokens(NullNode.getInstance()),
        Class.forName("java.util.Optional", true, Thread.currentThread().getContextClassLoader())));

    // works as expected
    {
      TextNode parameter = TextNode.valueOf("test");
      Class<?> type = Class.forName("java.util.Optional", true,
          Thread.currentThread().getContextClassLoader());
      Object value = mapper.readValue(mapper.treeAsTokens(parameter),
          type);
      System.out.println(value);
      // prints Optional[test]
    }

     // works as expected
    {
      TextNode parameter = TextNode.valueOf("test");
      JavaType type = TypeFactory.defaultInstance().constructType(Optional.class);
      Object value = mapper.readValue(mapper.treeAsTokens(parameter),
          type);
      // throws exception
      System.out.println(value);
    }
}

Here is the stacktrace:

Exception in thread "main" com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Java 8 optional type java.util.Optional not supported by default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jdk8" to enable handling
at [Source: UNKNOWN; byte offset: #UNKNOWN]
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1888)
at com.fasterxml.jackson.databind.deser.impl.UnsupportedTypeDeserializer.deserialize(UnsupportedTypeDeserializer.java:48)
at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:342)
at com.fasterxml.jackson.databind.ObjectMapper._readValue(ObjectMapper.java:4904)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3105)

Expected behavior

The last code block should work and return Optional[test].

Additional context

The error message is wrong all the way, as the Jdk8Module is in place.

I tried also with a POJO including an Optional field with the same result.

[JooHyukKim]

Seems like the underlying issue (actual error) is being wrapped at unexpected point?

[cowtowncoder]

Likely due to handling by Optional deserializer by Java 8 module, transferred.

[cowtowncoder]

Quick note: problem is somehow due to use of:

JavaType type = TypeFactory.defaultInstance().constructType(Optional.class);

which really should instead be

JavaType type = mapper.constructType(Optional.class);
// or
JavaType type = mapper.getTypeFactory().constructType(Optional.class);

and making this change code works. TypeFactory.defaultInstance should not be used by application code, ever.
But I'll see what specifically causes fail at lower level & see if that can be avoided.

[cowtowncoder]

Ok this is because of Jdk8TypeModifier missing when using TypeFactory.defaultInstance.

[cowtowncoder]

Work-around added for 2.18(.5), 2.19(.3).

[mattlocker]

Wow! Thank you very much for your quick response, detailed analysis and implementation of a the work-around!