Inheritance: Could not resolve subtype (multiple candidates)

[Karsil]

Hey everyone,

I'm trying to solve an inheritance problem where a clear deduction is currently not possible. A toy example:

// BASECLASS
@JsonSubTypes( {
@JsonSubTypes.Type( Child.class )
} )
@JsonTypeInfo( use = JsonTypeInfo.Id.DEDUCTION )
public class BaseModel
{
@JsonProperty( value = "baseOne", required = true )
@JsonPropertyDescription( "some value of base class" )
protected String m_valueOne = "defaultValue";

@JsonProperty( value = "basTwo", required = true )
@JsonPropertyDescription( "another value of base class" )
protected String m_valueTwo;

public BaseModel()
{
}

public BaseModel( final String p_value )
{
m_valueOne = p_value;
}
}

// CHILD CLASS
@JsonInclude( JsonInclude.Include.NON_NULL )
public class Child extends BaseModel
{
@JsonProperty( value = "childValueFirst", required = true )
@JsonPropertyDescription( "some value of child class" )
private String m_child;

public Child()
{
}

public Child( final String p_value )
{
m_child = p_value;
}
}

// TEST
public class TestDemo
{
@Test
public void testDefault() throws JsonProcessingException
{
final List<BaseModel> l_list = Stream.of( new BaseModel(), new Child() ).collect( Collectors.toList() );

final ObjectMapper l_mapper = new ObjectMapper();
final String l_json = l_mapper.writeValueAsString( l_list );
System.out.println( l_json );
final List<BaseModel> l_out = l_mapper.readValue( l_json, new TypeReference<List<BaseModel>>()
{ } );
}
}

Error message (during deserialization):
com.fasterxml.jackson.databind.exc.InvalidTypeIdException: Could not resolve subtype of [simple type, class testproject.demo.BaseModel]: Cannot deduce unique subtype of `testproject.demo.BaseModel` (2 candidates match)

The error is quite logical: For the base class, two possibilities can actually be deserialized.

I already have encountered the defaultImpl property:
@JsonTypeInfo( ..., defaultImpl = BaseClass.class )
But this leads to a high-priority, default behaviour (all child objects are deserialized with this default class, which is not intended). I'd rather like to give it the lowest priority.

But how actually to solve this? Thanks in advance for any help!

[Karsil]

Duplicate to https://groups.google.com/g/jackson-user/c/xOGWntrDoRI

Can be removed.