Cannot deserialize Throwables with Jackson databind 2.9.4 using @JsonIdentityInfo

I have written a test case that reproduces this issue. Object mapper configuration:

`

private ObjectMapperAccess() {
    this.objectMapper = new ObjectMapper();

    /**
     * Generic configuration
     */
    this.objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.NONE);
    this.objectMapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
    this.objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL, JsonTypeInfo.As.PROPERTY);

    /**
     * Configure deserialization features
     */
    this.objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

    /**
     * Register mixins
     */
    this.objectMapper.addMixIn(Throwable.class, ThrowablelMixin.class);
    this.objectMapper.addMixIn(StackTraceElement.class, StackTraceElementMixin.class);
}`

Mixin definitions:

@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class) public abstract class ThrowablelMixin {}

public abstract class StackTraceElementMixin { // With this property name and getter name will be the same. @JsonProperty("className") private String declaringClass; }

Test case that fails:

`

private void generateException() {
    try {
        Integer.parseInt("invalid_int");
    } catch (NumberFormatException e) {
        e.printStackTrace();
        throw new RmiHttpRuntimeException("Could not parse", e);
    }
}

/**
 * Test mixin for StackTraceElement.
 */
@Test
public void testStackTraceElementAndThrowableMixin() throws IOException {
    try {
        generateException();
        Assert.fail(String.format("%s did not occur.", NumberFormatException.class.getName()));
    } catch (RmiHttpRuntimeException re) {
        re.printStackTrace();
        String json = objectMapper.writeValueAsString(re);
        System.out.println(json);
        RmiHttpRuntimeException pre = objectMapper.readValue(json, RmiHttpRuntimeException.class);
        Assert.assertFalse(pre.getStackTrace()[0].getClassName().isEmpty());
        //TODO figure out a way to de/serialize cause.
        Assert.assertNotNull(pre.getCause().getStackTrace()[0].getClassName());
    }
}`

Exception message and stacktrace of the above test case:

com.fasterxml.jackson.databind.exc.InvalidTypeIdException: Missing type id when trying to resolve subtype of [simple type, class java.lang.Throwable]: missing type id property ‘@class’ (for POJO property ‘cause’) at [Source: (String)“{”@class":“com.netapp.oci.platform.http.RmiHttpRuntimeException”,“@id”:1,“detailMessage”:“Could not parse”,“cause”:{“@class”:“java.lang.NumberFormatException”,“@id”:2,“detailMessage”:“For input string: "invalid_int"”,“cause”:2,“stackTrace”:[{“methodName”:“forInputString”,“fileName”:“NumberFormatException.java”,“lineNumber”:65,“className”:“java.lang.NumberFormatException”},{“methodName”:“parseInt”,“fileName”:“Integer.java”,“lineNumber”:580,“className”:“java.lang.Integer”},{“methodName”:“parseIn”[truncated 6895 chars]; line: 1, column: 228]

at com.fasterxml.jackson.databind.exc.InvalidTypeIdException.from(InvalidTypeIdException.java:43)
at com.fasterxml.jackson.databind.DeserializationContext.missingTypeIdException(DeserializationContext.java:1638)
at com.fasterxml.jackson.databind.DeserializationContext.handleMissingTypeId(DeserializationContext.java:1217)
at com.fasterxml.jackson.databind.jsontype.impl.TypeDeserializerBase._handleMissingTypeId(TypeDeserializerBase.java:300)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedUsingDefaultImpl(AsPropertyTypeDeserializer.java:164)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:88)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeWithType(BeanDeserializerBase.java:1171)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:527)
at com.fasterxml.jackson.databind.deser.std.ThrowableDeserializer.deserializeFromObject(ThrowableDeserializer.java:103)
at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:194)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:161)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:130)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:97)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeWithType(BeanDeserializerBase.java:1171)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:527)
at com.fasterxml.jackson.databind.deser.std.ThrowableDeserializer.deserializeFromObject(ThrowableDeserializer.java:103)
at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:194)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:161)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:130)
at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:97)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeWithType(BeanDeserializerBase.java:1171)
at com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:68)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4001)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2992)
at com.netapp.oci.platform.http.jackson.TestObjectMapper.testStackTraceElementMixin(TestObjectMapper.java:116)

[kreiger]

cause of a Throwable points to itself. That is wrong and really should be fixed.

It is not wrong. It is the default behavior of Throwable when no cause is given.

From Throwable.java:

/**
 * The throwable that caused this throwable to get thrown, or null if this
 * throwable was not caused by another throwable, or if the causative
 * throwable is unknown.  If this field is equal to this throwable itself,
 * it indicates that the cause of this throwable has not yet been
 * initialized.
 *
 * @serial
 * @since 1.4
 */
private Throwable cause = this;

…

public synchronized Throwable getCause() {
    return (cause==this ? null : cause);
}

[cowtowncoder]

@sholavanalli I think the main question is that of why @JsonIdentityInfo is being used. Would it be possible to just eliminate it?